Since our ancestors climbed down from the trees, human history has been, among other things, a continuous series of cultural appropriations. If you doubt this claim, just walk through a mental experiment. Recreate what in overwhelming likelihood would have happened absent such cultural appropriation, by which each band or tribe adopted the practices and acquired the knowledge possessed by other bands or tribes. In this (non-appropriating) case, human beings would still be living in small bands subsisting, if at all, by gaining a precarious livelihood digging edible roots from the ground and edible insects from the bark of trees, with wild fruits and berries or a game animal added occasionally if they were lucky.
Cultural appropriation has been our salvation and our glory as a species. It is the way in which discoveries and inventions have been disseminated among the human population. To condemn it is stupid.