There is so much to unpack here and so many specifics I’d love to jump on but with 5 pages already, it is impossible especially considering I'm a fact checker to a fault. To stay on topic, I think the issue of cultural appropriation is largely overblown as we’re all living in one large culture, Western culture, that pulls from all cultures that it is made up of. It was stated somewhere earlier in this thread, and stated by Bill Maher, that most people that get pissed about racism and cultural appropriation are white people that are being angry for everyone else. I cannot agree more. I can see the issue with Native head dresses, and such, but I’m sorry, blacks have zero ownership of dreadlocks. Dreadlocks, as a hairstyle, evolved in different unrelated cultures over thousands of years.
A Cree Nation Chief in 1885
Greek wrestlers, 1800 BC
It was documented as far back as the 7th century BC in Poland (what eventually became Poland) and up to the 19th century as well.
Indian ascetic monks, Spartans, some Tibetan monks, etc. Dreads have been worn in many cultures for almost 6000 years.
In a multi-cultural environment such as North America and Western Europe, "cultural appropriation" as it stands today is nothing more than a bottomless pit of excuses for people to bitch and complain when they really have nothing better to do. There are obvious examples that we can all agree upon as exceptions. For instance, the absolutely disastrous attempt by the democrats in the US Congress to appease to their Twitter base by kneeling while wearing Kente cloths is one such example. None of them would be caught dead wearing a Kente cloth outside of that one photo-op and many of my black friends and family thought it was ridiculous as well. So to answer the OP's original question, cultural appropriation is when someone takes issue with how another person dresses, cooks, speaks, sings, or generally presents themselves because it is "stealing" that behaviour from another culture, while the person offended is guaranteed to be doing the same thing, as we all are, in a culture made up of literally dozens, if not hundreds of other cultures at the same time.