Have Vinland be a bit more successful, becoming a moderately self-sustaining nation covering much of Newfoundland, before getting cut off from their Norse peers and mostly forgotten.
Smallpox and other European diseases reach America early and spread through the population over the next few hundred years. There are mass population dieoffs but the populations recover over the next few hundred years.
Also, some of the natives might learn the seafaring skills of the Vinlanders.
When Columbus comes half a millennium later, there are no mass dieoffs from disease, the natives can resist European colonisation more, and the Americas become an Africa analog, of a land where the natives are oppressed and ruled by overseas powers, but always remain a majority.
Alternatively, could a native farming civilisation exist on the Mississippi, akin to Egypt?