As my dear friend Donald J. Boudreaux says, you can’t unjustly appropriate something that didn’t belong to anyone in the first place. No one owns a culture.
Cultural appropriation, like many of the rhetorical weapons wielded in the culture wars and the politics of group identity, is a silly notion. I doubt that there is a single culture on earth that does not consist largely if not entirely of elements taken at some point from other cultures. The cultures of the world are a complex and ever-changing conglomeration produced by such interchanges. But each adoption was made for a reason, for an expected benefit. A world without cultural appropriation would be a worse world, but worry not: such a world is impossible in any event.