First off, this is a linguistics question. You'd have to know a lot of distinct languages to even give a representative answer.

Second, there's a usage problem. A continent is a very large contiguous body of land. For a precontact Indian the land was virtually all contiguous. There were no continents, there just was the Earth. Words which would come to be applied to that idea wouldn't have the same connotations of the classical distinction by which Westerners have decided on continents.