It is important to note that Spanish colonization and English colonization had very different strategies. Spanish colonization tended to replace the existing power structures with their own, which typically preserved the native population even if they were demoted to being second class citizens. In contrast, English colonization was a more a form of genocide combined with a settler colonization of free and enslaved persons. There are few tribes east of the Mississippi that are federally recognized and many tribes were forcibly relocated by English and later American government forces.

And I don’t know how it was in South America, but North America saw a collapse of civilization near first contact which shaped English colonization. There were several Native American civilizations with complex urban forms which collapsed by the time there was contact with English/American settlers. A few remained like the Iroquois and Cherokee, but there was seen to be an overall regression which settlers took as a sign from God that they should settle those lands instead.