Only going to address the part that we've both acknowledged as the only part I care about (I'm on lunch and I'm not wasting the whole thing debating dumb shit):
Changing a fictional character in an established IP into something else for the sake of diversity is a perversion of art. Period. If you want more black superheroes, literally nothing is stopping you from making them. Comic fans (see: actual comic fans, not MCU fans and "OMG im such a nerd" fans) generally don't like it when the main canon of their favorite IPs is altered for no good reason.
If you can't make Miles Morales white, you can't make Peter Parker black. If you can't make Batwoman straight, you can't make Bobby Drake gay. Just because a race/gender/sexuality/identity is over-represented doesn't give everyone agency to change then into whatever they want while claiming the reverse is against the rules.
I mean im replying to your whole reply, hence the first part, just calling them as I see them. And since you more or less reiterated your point, all we can really do is agree to disagree since I cant really say much more tha reiterating mine. One thing I will say though is that since you're zooming in on comic books a bit, most of the time, movies are entirely new canons where being as accurate as possible doesnt realy matter, making Johnny Storm Black matters as much as changing Thanos' motivations, which both happened because it is a different medium where things are gonna be altered.
Except the part where most people knew it was going to be trash from the get-go, meaning the improv isn't what liked it.
People knew it looked bad because the trailer wasnt funny, and the trailer wasnt funny because the humour is bad, and the humour is bad because improv.