“Why do we limit ourselves to a single migration theory?”
Good question, and good reason for anyone to remove themself from the collective “we” in that question.
An intelligent person should realize we are in kindergarten when it comes to understanding the human past (any of it) in the western hemisphere, and just as ignorant in understanding the human past in Eurasia prior to 4 or 5,000 B.C.
No one should believe most of what the archeologists say as more than theories.
They don’t want conclusions...they want GRANT MONEY!!