American culture is nothing more than the appropriation of language, culture, music, art, style, etc. from other countries. We didn't even invent "English" which is why we speak English instead of American. Though the English would say we didn't even get "English" right.

What makes American culture, American culture is our tendency to put an "American" twist to those things. Like going on "vacation" instead of "holiday".

Cultural appropriation defines American style and culture. It is not done to offend those cultures; it is done because Americans are in constant search of the "next new thing" rather than preserving the past and we don't really care where that "next new thing" came from. My Korean friends celebrate Thanksgiving even if it is not part of their culture and they serve Kimchi with their turkey. Should I be offended they eat turkey? Or rather celebrate the fact, that they find this uniquely American tradition worthy of enjoying? I choose the latter.

If at some level, people intentionally represent some "new thing" as entirely "original", when it is not, that is a "kind of plagiarism". But claiming something as new is different than enjoying something from another culture.

Likewise, if someone intentionally diminishes someone else's culture that can be offensive. But simply adapting something from another culture is at some level flattering. For as the saying goes...

Imitation is the sincerest form of flattery...