"You don't hear people using the world 'discovery' anymore like they used to. 'Columbus discovers America.' Because how could he discover America if there were already people living here?"

Well, discovered by Europeans, obviously, dumbass.

There would not be as many Indians as now, thanks to Euro agriculture.
The Indians would be warring, enslaving, and eating each other. They
would be without Euro medicine, science, technology.

Guns germs and steel.