Right, well during the age of sail we had already achieved gunpowder, steel and iron working, and landing on small islands with navigation era tech it is quite

Right, well during the age of sail we had already achieved gunpowder, steel and iron working, and landing on small islands with navigation era tech it is quite easy to dominate or change a small ecosystem by cutting down trees, hunting excessively, introducing livestock and other invasive species, etc. In the ice age the tools were bone and stone. And the lack of agriculture meant that human populations were kept small by available resources by default. The lack of transportation or even domestication of animals in the Americas at the time meant that all travel was on foot. To dominate species like the mastadon, giant ground sloth, cave bear, dire wolf, etc on two continents was just something humans weren't capable of at the time. Hunting was still risky and labor intensive. Arrows didn't have metal heads. Range was limited. Traveling was risky, both from natural and tribal threats. It just doesn't add up. The density of humans was probably lower in the Americas than in any other continent (save for Antarctica of course).