> when a non-male or non-white protagonist is the only option
There’s a difference between a racist or sexist reaction (anger about a character’s race or sex) and anger that the studio picked the character’s race or sex as a nod to their own identity politics (or perhaps kowtowing to the broader identity politics that are so fashionable these days). It’s the same difference between racism and equality. It’s hard to tell from your comment whether you object to the racist reaction or the egalitarian reaction or both, but at least in my opinion the racist reaction is very uncommon.
> Just saying, in my experience, "don't care about it" is literally identical to "marginalize everyone but me", as that's our history.
That’s not our history though; our history was literally “marginalize blacks, women, native americans, italians, irish, eastern europeans, asians, etc”. We have made remarkable progress toward equality, and that’s due to egalitarianism—teaching people that superficial characteristics oughtn’t matter—not merely a different identity hierarchy. “Not caring about it” is precisely the key innovation and the catalyst for so much progress.