Good point. South America would probably look like Africa (with the Inca as Ethiopia). North America, however, is generally better for nation-building thanks to geography - an interior dominated by large plains fed by massive rivers, not desert or jungle. Given the right tools, the Native Americans could make a pretty good go at real nation-building in the interior.

I would just like to point out that you're suggesting exactly the opposite of historical development. Not just the Inca in South America, but the Guarani also had developed sedentary agriculture and high population densities, and the Mapuche even developed nationalism independently and were able to remain independent by playing diplomacy better than the Spanish and defeating them in battle (Valdivia, Chile was razed to the ground 3 separate times as the most obvious example).

The key lies in population densities. North America has some helpful geography as you say, but there were so few people compared to South America that their development lagged.

I find it more likely that South America would be on the development level of Southeast Asia, whereas North America and the Caribbean would be more comparable to Africa. The plains of North America can still be colonized in this timeline due to population dynamics.