I have never heard of American Indians (aka Native Americans) called Aboriginal in any form of that word. It is usually reserved for Australian natives.

The American Indians are from many different backgrounds and different groups came a different times over a period of approximately 30,000 years.

The Eskimo, I believe are "oriental", the notheastern tribes are largely "caucasian" and the Artic groups are related to other Arctic peoples in Siberia, etc.

That leaves the soutwestern tribes and extending south through Mexico and South America. Some feel that these are a differnt "race" called Proto-Australoid which produced the American natives as well as the Australian natives, but they themselves are now extinct.

I have read three books on the origins of American natives and my conclusion is that all experts make educated guesses. Not a very exact science.