Use your imagination. If Columbus had never come here, and other enlightened Western and Eastern populations decided to allow the America's to continue without outside interference, the indigenous people here would probably still...
- have no real written language,
- have not invented the wheel,
- have no animals sufficiently domesticated to do work,
- have not invented iron or steel, or any other metal sufficiently hard to make a durable blade,
- have no gunpowder or other substance capable of explosion,
- be practicing human sacrifice and cannibalism,
- have average lifespans in the 30-40 years,
- have nothing resembling actual medicine, as a skill or practice,
- have no idea of the shape of the earth or what lies outside what is visible from American shores,
...you get the idea.
The best thing that ever happened to the indigenous people was the "invasion" by Europeans. Just like the best thing that ever happened in the family histories of African Americans was the transporting of their ancestors to these shores, as slaves.