If the people who colonized North America from Asia and inhabited the region prior to the arrival of people from Europe really were soloing the cliffs in the region, then climbers would be finding traces of their presence up on the cliffs, which as far as I know, we aren't. Most modern 'white men' aren't so stupid as to go and solo some dirty unknown crack. Personally, I suspect that most North American aboriginal people were just as smart.
Native Americans aren't fucking magical, they're people just like you and me.