N. America: Failure

My U.S. History text doesn't give me a lot of faith for the northern continent. It seems like a nice little failure from the start, North America.

The Native Americans cross the Land Bridge into Alaska. Too cold. They migrate south. They migrate to Southern America for the most part; some of them stay in Canada, some of them stay in what is now the Continental United States, but the Incas, Mayas and Aztecs are all below the U.S. border (except I believe the Aztecs originally stayed in what is now Texas [admittedly Mexico originally anyway], and later migrated south into Mexico). The Incas, Mayans and Aztecs all had denser populations than the North American Indians and more advanced, sophisticated cultures. They had art, warfare, science, the whole shebang (excluding ships, but they'd already worked so hard to get to South America, why would they bother leaving?) and it was harder to conquer them than it was to conquer the North American Indians. Iroquois got nothin' on the Aztecs, sorry. Just the way it is.

Now, those are just the ancient cultures. Advanced for their time, location, and whoa! lack of access to Europeans, who we all know were waaaay better. Pshaw, obviously.
South America was conquered by the Spanish and the Portuguese, for the most part anyway, and I don't know about the Portuguese but the Spanish are supposed to be some of the best lovers in the world. You know that's how they conquered South America: they loved those natives 'til they wore out. They didn't even need warfare; that's just what history says to avoid being awkward.
South America was loved into conquest. The English had to slaughter the North American natives, but that's also just according to history's not wanting to be awkward. Really, the English bored the natives to death. Can you imagine, whole cultures slaughtered by boredom. I'm glad my ancestors weren't English, or involved in slaughter with the sword of Ennui.