To summarize:

1.Movies don't always stick to the source material. Please don't act like this would be a first. Some changes killed characters off before their time and we were ok with that. Changes are applauded or criticized negatively after we watch the movie and learn about how they incorporate these changes. A new twist about someone's sexuality isn't going to be as impactful as a premature death of one of your beloved characters. Yet, you are already objecting.

2.What's wrong with pushing a noble agenda using a popular character to promote acceptance world-wide? Lots and lots of movies do that, at least it's not agenda about going to war or sleeping with your pets.

3.Spider-man is not Stan's Lee property. I am pretty sure he didn't like all of the changes that were inflicted to his characters even if they were received warmly by the critics.

4.The human torch used to be a white guy. Now he is black. Why is this OK and pansexuality isn't? It's just sex in a popcorn flick, get over it.

And one last thing:

The creators of The Bing Bang Theory gave an interview many years ago and said that Sheldon won't have a girlfriend. He's different than everyone else and that's actually fine. They clarified that he's not gay, but he doesn't have the same needs that other characters have so he will remain single. I think they said that Sheldon having a gf would go against their vision.

Fast forward a few years later and not only does he have a gf, he wants to marry her. Now, whether the creators were pressured by CBS or changed their minds on their own is debatable and perhaps we'll never know. But it goes to show that just because the creator(s) says something, it doesn't meant this will remain to be true or becomes cannon.

No, the time was 1993!

I have not made any insults aimed at you.  Have you read comics?  If not, then you're speaking out of your ass and should go pick up some comics before trying to speak more on the subject.  Have you read comics and still think Spider-man might be attracted to men despite no evidence to support it?  Then you definitely need to get your head checked, or at least do some studying on literary anaylysis and the nature of evidence, because what you're suggesting is totally unfounded.  And I respond the way I like.  If you find something that you legitimately think is offensive, you have a report button for that very reason.  

Second "we can say with about99.99999999% certainty that he is not gay". No we cannot. It's not that simple and percentages really mean nothing if not backed by evidence. In this case, you'd need a scene in the comics (that is cannon, not a parallel universe) where he's really old and he talks to someone like Jean Grey (who is actively reading hsi mind) and tells her he never had any feelings for men. 

And this is why I say things like that.  Do we really need a scene where Spider-man is essentially hooked up to a polygraph test and saying he's not gay to prove he's gay?  Cause that's laughably ridiculous, so don't get offended when I point that out.  Do we need to get a DNA test on him to prove that Aunt May is actually his aunt?  Should we force Mary Jane to grow out her hair to prove she's actually a red head?  Do we need to get a metallurgist to verify the makeup of Captain America's shield?  Why the ridiculous standard of evidence required for this particular claim?

But, if you want to talk about evidence, fine let's talk about it.  My evidence that Peter Parker is a heterosexual-

He's dated women.  He married a woman.  He had a kid.  We know from his internal monologues that he has been attracted to many women.  No telepath or person taking over Spider-man's mind has said anything about him being gay/bi/pan/whatever, even though Otto Octavious specifically went after Spider-man's love interests to prove himself the superior Spider-man.  We as the readers are privy to his thoughts, and those thoughts have never included anything about being attracted to men.  

Let's focus on that last one since you want to talk about evidence.  In science you have a hypothesis.  Your hypothesis is that Peter Parker is attracted to men.  Now, a theory should be predictive.  So, it should make some measureable and testable predictions.  It seems like a reasonable prediction that if Peter Parker was attracted to men, then each time he meets a man, of which he has met thousands, there should be a chance that he'd be attracted to him, especially since he's met dreamboats like Johnny Storm and Steve Rogers.  And, since most comic books are told from Peter Parker's first person thoughts or an omniscient third person narrator, we should see some sign of his attraction to men in thought bubbles, dialogue, or narration.

So let's run our test.  Out of 10000+ encounters with men throughout Spider-man comic books, the rate of Spider-man showing any signs of attraction or romantic interest is 0%.   Simply hasn't happened.  So, we have to reject the hypothesis that Peter Parker is attracted to men, and accept the null hypothesis that he is not attracted to men.

So then, present evidence to the contrary.  And if you cannot present evidence but you still insist that there is any real possibility he's attracted to men, then yes, you need your head checked.

You seem to have a very limited understanding of sexuality and that's fine. You may wanna educate yourself or keep your current thoughts, but I can tell you that just because you've known gay people, it doesn't mean you know everything there is to know. With limited knowledge, you are bound to make generalizations. Also, I was not referring to closeted cases; neither was I talking about Parker wanting to have sex with a man. Sexuality is not only about sex.

I'm all ears  then.  If something I said is wrong, I am happy to be corrected.  But yes, you were talking about closeted cases, because if Peter Parker was attracted to men, and it has never come up over about 30 years of life, then he definitely was closeted.  And yes, we are talking about sexual interest, because that was the context for the conversation.  

The story could be something as simple as Peter in his teens spending time with a new friend and developing feelings for him. He can have feelings for a man and a woman and show us how he's questioning his sexuality. This is not unheard of for people in their teens. Even if he does end up realizing that he's bi/pansexual, it doesn't mean that he must have had a relationship with a guy later on.

1.  Peter Parker didn't have friends in high school.  His closest male friend in his youth was Harry Osborne, and that's established as a platonic relationship.  Peter, in 616 and Ultimate incarnations, actually showed far more interest in females in his teen days.  

2.  It's not unheard of for people in their teens.  It is unheard of for Peter Parker, because we never heard about it. 

3.  What you're suggesting is retconning.  Changing established continuity and creating something in the past that never happened.  If this happened, then yes Peter Parker would be gay/bi or whatever.  But, it didn't.

4.  If he's not going to have a relationship with a guy, then what the hell is the point?  Why go through the effort to inject some homoerotic stuff into Peter's past to not have any follow up?  That's just shitty storytelling.  Like, seriously why?  Just to say "hey readers, just so you know, Spider-man liked this dude once.  Not important for any reason, but just so you know."

5.  You're not actually making a case for Spider-man liking dudes, you're just kind of saying that it would be neat if we got some gay Spidey fanfic.  And if we're going to do gay fanfic for marvel characters, this is a terrible choice.  Seriously, Bucky and Captain America.  Two warriors who find love among the horrors of world war II only to tragically be torn apart and then awaken years later to face eachother as enemies on the battlefield.  That's a way better story then "hey Spider-man met this cute guy once and he kind of liked him."

1.   it doesn't have to be beneficial. It doesn't have to affect it negatively. You insist it would and your reasoning? the source material. Which we already established no one gives a shit about as proven by the movies that generate billions of dollars despite beind different. You care? don't watch, simple.

If it doesn't effect the story in any way, then it is a pointless change, and shitty writing.  And no, we didn't establish that you can just chuck the source material to the wind and still have success.  Most of the movies that are making billions are keeping most of the source material. 

And, if you actually read what I said, I did not say anything about never changing the source material.  I said that you have to have a reason to change the source material.

2. I'm not sure what point you're trying to make here.  That some people will like it and some won't?  Yes, and I won't like it.  That's why I'm complaining about it.  That's what we call "expressing your opinion".    And saying "tough" is not any sort of meaningful response.  It's just saying that you don't care about my opinion, and you don't have to.  If you don't, that's fine, but when you're posting in an opinion based topic, it's kind of a pointless.  Basically the equivelent of shoving your fingers in your ears.

3.  You keep saying this and it's ridiculous every time.  First of all, who cares how much money they're making?  Unless you're a Marvel executive, that is completely meaningless.  The amount of money they make has nothing to do with the quality of the movie.  And even if it did, this is still an incredibly dumb point, because to make it meaningful, you'd have to isolate the variable (change from source material) compare it to how much money the films are making, and then analyze how changing the source material impacts things.  And even then you're be left with a stupid argument, because each change would have to be viewed differently.   Making the Vision based on Jarvis and not Wonderman won't necessarily have the same impact as making Spider-man pansexual.

The trend in comic book movies has actually been moving closer to the source material.  The new batman movies are far closer to the source than the older onese, and have made more money.  Marvel's incarnations of their characters tend to be far more closely linked to the source material than movies made by fox and Sony and have been making a lot more money.  We have movies like Catwoman, Fantastic 4, and Daredevil that completely ignore their source material, and bomb.

So what data do you have to suggest that changing source material does not influence ticket sales, and better yet, why should we care about how much money the movie makes in the context of this conversation?

4.  Since you went with a complete non-sequitor instead of addressing the point regarding the human torch, I'm going to guess you have nothing intelligent to say on the matter.  Skin color and sexuality are not the same thing.  One has an inherrent impact on how you act, and one does not.

I'm fine with whatever they want to do, I just don't see a Spiderman film that shoves a "hey look, Spiderman is gay" in our face is going to attract a very big audience. Teen Titans have Bunker, who is a gay latino male. They should make a Teen Titans movie.

That's more of a Deadpool thing, but I get your point. Spider-Man is quirky and funny most of the time, so that could go up his alley. I'm not against a pansexual change. Hell, I'd be up for it. But would that be credible for the storyline? I mean, would a pansexual Spider-Man bring something relevant for the overall storyline? I believe it can bring an interesting side story, but I personally wouldn't want them to make it a selling and marketing point. Not to mention nitpickers and haters spewing their hatred all over the internet just to end that story because they want it to go back to normal.

Okay. Here's the other side. Say you found a gay character comic. You read it for 20 years. You invested into that character, as any real person. Then the writers decide to make them straight. You'd be on the other side. Make a new character for this. Not alter one.