I'm glad you brought up the contrast between the Aztecs and Ottomans - the majority of South America was inhabited by tribes similar to Native Americans in the North.

The Aztecs are noteworthy because of having an empire to conquer.

I am not suggesting that their civilizations did not have artistic or cultural merit, but I think even in a fictional alternate history where the Spanish decided to peacefully trade with Montezuma, I bet a couple hundred years later these people would've had mechanical looms and walked around in tailored suits just the same as their European counterparts.

Not to speak of an what an empire gaing such powerful technologies and ideas about running society would've done to its neighbors.