I don't think that a few sentences can do a complicated topic justice, but it would folly to point out what you are saying without also acknowledging that Europeans are indeed the people that brought that specific form of slavery to Native Americans. No Europeans, no Native American ownership of Africans, but I agree that a holistic view of Native American culture should be presented in textbooks, etc.

Claudio Saunt, the historian who wrote the Aeon article above, is quite literally a leading expert on this exact topic (see his book "Black, White and Indian" with Oxford University Press).