Regardless, you have a point here. To try and debunk your point we have to get into the weeds of what constitutes a villain or not. The black lady in Loki isn't a villain, she's just a TVA agent doing her job. And literally every non-white-man villain in the MCU has quickly turned out to mean well and join the heroes. Adversary doesn't mean villain, like you said. There have been a bunch of adversaries who were non-white-men over the MCU but I challenge anyone to name a single one who was actually evil or irredeemable like most of the main villains have been. The only possible answer I can think of is Killmonger and he was, as you said, given an out with his backstory explaining why he was the way he was and how his goals were on some level actually noble in their own way. Edit: Oh yeah, and Mordo. I guess there's that one.
Kang the Conqueror would be the first really vicious/dangerous/evil non-white-man antagonist in the MCU...and I'm pretty sure he'll just end up being blue anyway.
It might not be high on my list of concerns, but people who point these things out aren't exactly wrong. It's framing things a certain way for a mass audience and I'm not sure if their motivations are entirely altruistic, as opposed to the pushing of a certain undermining ideology that's been making the rounds.
Ambiturner
Oh okay, I thought it was the guard. Totally forgot about the judge.
