Every Native American stands on ground that once belonged to someone else. Their bones are here; why do none of their genes survive? How did those now calling themselves Native Americans come into possession of the land?
There is no clue about who came first or how they got here. It is fairly certain that they did NOT cross the Bering Sea on a land bridge.
If you search for images of "Olmec", a Mexican culture, you get stone heads with distinctive African faces, but nobody wants to talk about the implications.