Okay. So then we agree that what we're discussing is one culture adopting the traits and symbols of another culture. And we agree that's not the same as theft. It's "appropriation."
So is appropriation bad? And if so, why is it bad?
It seems like the main gripe here is that appropriation of certain cultural traits by ONE culture may potentially redefine those traits in the original culture.
Can we say that black people "appropriated" white musical theory to create Jazz? Is that equally bad?
I do not think appropriation is necessarily good or bad. It doesn't even have to be race oriented, tbh. NY rappers have appropriated a southern rap sound. It can be a negative thing when a people is totally stripped of their original culture, institutionalized, and well...
But it is not at all unfair to check or resent white people, specifically, for latching onto and capitalizing on black culture (for the sake of this example) after they very brutally stripped black americans of all sense of identity. So thoroughly that the effects are still very apparent today. Even as free men, blacks have had to deal with being treated as subhuman. All the while our music, dances, slang, art are loved
now. What are we supposed to think other than "Y'all keep stealing my shyt!"? HipHop gets an 'Elvis' every once in a while and people love it. This same shyt happened to rock and roll but at least The Beatles admitted it while they were in it. I digress, tho. It's so bad at this point that one of the only constants in the general 'black culture' in the US is 'how do you deal with white people?'. Our culture is based on paranoia half the damn time, albeit paranoia turned towards cunning.
Once discovered by an outsider, any cultural practice or artifact can be spread. That's just the nature of the game, but we must always consider the context, you know? I'm an adult and I should practice safe sex. However, I should not have safe sex with an animal in a daycare full of children with progeria. That is why it's still largely unacceptable for white people to say 'nikka'.
I also believe that most people will disagree (if not laugh in your face) if you tried to give white people any credit for pioneering jazz music.

although many were classically trained...that's a whole other thread.