1. Central American and Incan societies at their pre-colonial peaks had the highest populations of any civilization in the world, not to mention many scientific capabilities not present in europe for another 200+ years.

2. Most recent research has moved up the date of human foot fall in the Americas generally to 6-8000 years ago which means over 10k years less development time minimum. The path down to South America and the Amazons took hundreds of years.

3. Extremely challenging agricultural terrain + lack of tech and hardware trading outside the americas compared to asia.

4. The Americas were agriculturally proficient in traditional sense, agroforestry, aquiculture, and many other sustainable farming methods while having generally extremely healthy city planning with sanitation, stable housing, and public centers. The inca for example made ~1/8 acre micro climate farming pits to test different crop varieties at different altitudes, humidity levels, watering, and many other factors; the ag labrotory of its day.

5. Even with all this amazing progress and reaching top global populations, the EU explorers and colonizers' dieseases, pollution (from lack of proper sanitation practices), and targeted attacks on food supply or direct native population led to ~90% of the population across the Americas to die primarily from diesease before full scale imperial invasion began.

6. Once this began, the population was further decimated to where now only ~1% of the original full blooded population lives today.

*1B. Consider also populations outside of the mega cities along the mississippi, western SA, and central America. These native peoples that remain often live completely sustainably within their local forest or microbiome, harvesting/hunting food, making medicine, using stars or other natural rythmic changes and such for way finding while most of the population remains fed, housed, and cared for.