Weapons were never purposed to cause harm against other humans initially. They were meant to cause harm to the animals that needed to be killed for food, but those same weapons were looked upon as defense against predatory animals. When times were tough, and stealing became somewhat necessary, that's when the human intruders would take those same weapons and use them to cause harm to other humans with resources that were needed for the intruders to survive. That eventually led to the defending humans creating better weapons to ensure their own safety, which would eventually lead to those new weapons being copied or out done by even better weapons that the intruders would use.
There are still weapons where the main purpose is to kill animals, but most weapons today have the specific purpose of being a defense against or, mainly, to cause harm to other human beings.
Yes, that would be a further conclusion to my last post. Desperate times call for desperate measures. This is what eventually led to weapons being created in the more recent history of the world, for defense solely against other humans. Some of those weapons are of course, made in an efficient way so that they can also be used aggressively against other humans if necessary. Like I said before, once an intelligent being realizes that they can use other people to do their work, it becomes extremely hard to do the work yourself instead of just taking care of the much easier "dirty work". Sometimes the "dirty work" is hands off, and sometimes it's hands on. It happens all the time, everyday, and not just in terms of physically harmful weapons either.
Also, trying to say that guns are specifically designed to kill other people is incorrect. Guns are always about self defense first. Some of those guns are made so efficiently that they are extremely useful when used aggressively, but the point remains that the same gun would be even better as a defense weapon. You can't also say that certain guns are not made for self defense because it's "unnecessary". Depending on where you live in the world, what's necessary and what isn't, in terms of self defense, varies greatly. There is also the "what if" factor. While that is a more unlikely scenario, if your Country ends up in civil war, or another Country invades, or a chemical attack happens leading to hoards of zombie like people trying to kill you, having one of those "unnecessary guns" could be your saving grace. Trying to find one during or after the event, good luck, that's why having one right now isn't the worst idea, as long as it's not left on the front porch for someone to steal.
Even nukes, which seem an aggressive weapon, are not. The US didn't drop the few they did because they wanted to take something from someone else. They had been attacked and they knew at the time, that the enemy was more than willing to sacrifice every last one of themselves to keep their honor, so in self defense, the US killed so many, so quickly, in such a horrible way, it led to their enemy re-evaluating how important their honor really was in comparision to the potential extinction of their race, which led to the end of that conflict. The fact that even using a nuke as self defense today, could lead to entire Countries being wiped off the map, I would think at least a few people would be mentioning/protesting that. Instead we're way more worried about guns and a few death's. The fact that a nuclear war is less likely than mass shooting, doesn't mean it should be left out, if not completely off the table. Yet it seems that's exactly the case. Unless the news brings it up, it's not something to worry about apparently, until it ever happens God forbid, and whoever survives, will be begging for three main things. Food, shelter, and protection/a gun.