You could have the POD be whatever was so disruptive around 1300-1400 (New Madrid Earthquake? Destabilizing decades long droughts? Epidemics?) that substantially disrupted the Mississippian Civilization, the Anasazi in the Southwest, the Mexica, the Mayans, etc.. Without it(s), everythings quite a bit more advanced by 1491-1519 as the post-apolcalypse invaders from the North (Ute-Aztec, Apache-Navaho, Comanche-Kiowa) aren't able to sweep in and take over the disrupted and scattering communities.
Trade networks across the continents would remain in place for faster innovation diffusion (and more reason for shipbuilding in the Gulf and Coasts.)
The corn/beans/squash/pumpkins or potatoes/tomatos/peppers/beans cultures were already well in place and about 50% or more productive than contemporary European crops and farming practices so able to support very dense populations, bigger cities, more specialists, and more warriors.
Their advanced mathematics, engineering, biology, botany, astronomy are all excellent building blocks to match Age of Exploration Europeans given these 2 or 3 additional uninterrupted centuries.
It's hard to figure a workaround on the Age of Exploration's disease epidemics though. The Americas' had considerably more sophisticated medical, surgical, and pharmaceutical knowledge (often up into 1950's levels by the 1400's) so having them develop germ theory to a point that they were able to vaccinate early in the European plagues as least for smallpox, measles, etc. but those swept through so fast even a 1500 AD Mayan equivalent to the Center for Disease Control would likely be overwhelmed rather than solve it and cure it with "only" 1 in 8 or 1 in 5 dying instead of what sounds more like 1 in 2 or 9 in 10 dying.
Trade networks across the continents would remain in place for faster innovation diffusion (and more reason for shipbuilding in the Gulf and Coasts.)
The corn/beans/squash/pumpkins or potatoes/tomatos/peppers/beans cultures were already well in place and about 50% or more productive than contemporary European crops and farming practices so able to support very dense populations, bigger cities, more specialists, and more warriors.
Their advanced mathematics, engineering, biology, botany, astronomy are all excellent building blocks to match Age of Exploration Europeans given these 2 or 3 additional uninterrupted centuries.
It's hard to figure a workaround on the Age of Exploration's disease epidemics though. The Americas' had considerably more sophisticated medical, surgical, and pharmaceutical knowledge (often up into 1950's levels by the 1400's) so having them develop germ theory to a point that they were able to vaccinate early in the European plagues as least for smallpox, measles, etc. but those swept through so fast even a 1500 AD Mayan equivalent to the Center for Disease Control would likely be overwhelmed rather than solve it and cure it with "only" 1 in 8 or 1 in 5 dying instead of what sounds more like 1 in 2 or 9 in 10 dying.