Or, they had far advanced knowledge of working and remediating soil to grow food. Peat mosses, charcoal, household compost, are all valid soil additives that we now have scientific knowledge to explain how those benefit soil, but they were practicing it in soil that is otherwise unproductive. Given that no one else farmed it in that time it seems that knowledge was lost, but lines up with regenerative agriculture practices we see today.
I think they were just engaging in time-honored speculation about how different history could’ve been had a few historical accidents changed. For example, the Mayan civilization collapsed about 500 years before the Spanish showed up due to the worst drought in something like 7k years, so people have speculated about what Mesoamerica might have looked like when contact was made of those millions of people hadn’t died. Repeat for having draft animals, not losing the immune system lottery so badly, etc. Given their martial traditions it’s very plausible that in slightly different scenarios the arriving Conquistadors would’ve been killed or captured and lead to return expeditions.
The "immune system lottery" is really why the native Americans were doomed.
They could have caught up with the technology etc and stood their ground. But when 90% of the population dies at or before first contact, the remaining 10% doesn't have a chance.
Pretty sure this would have beaten the Mayas even if they were at the top of their game.
It's pretty wild how world history turned on such a random and completely unknown factor.
They also had a civilization knowledge base within them , which they could have mined. But there wasn't even a united south-north native empire.
There are several indicators in the south american jungles of civilisation going through booms and busts. If they would have been significant ahead, they would have colonized europe or china.