Before 1500 doesn't matter; after 1500, doesn't help
Throughout the Indian Wars, there were several attempts to create a confederation of Native Americans to defend against American expansion. Say one of these formed and was successful against America, what internal problems would it face and how long would it be before they boil over and tear the confederacy apart?
Before 1500 doesn't matter; after 1500, doesn't help.
Guns, germs, and steel is an understatement, but it really sums up the reasons a collision between neolithic peoples and the modern era is only going to end in one way.
The Western Hemisphere offered incredible wealth, literally beyond imagination, to the peoples of the Eastern Hemisphere as soon as technology was in place to transfer tens of thousands, hundreds of thousands, and millions of people across the Atlantic.
For the Columbian Exchange to not occur requires a fundamental change in human behaviour.
Good luck with that.
Best,