Oh, I agree but the ability to suggest 'settled science' ain't, is just so hard to resist. I am a firm believer in the axiom from the late great Arthur C Clarke which goes; "When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong."
My personal guesstimate is that the initial migrants probably came down the ice sheet in kayaks (skin boats) hunting and fishing and camping on shorelines long since flooded from the glacier melt. They had a clear shot down the west coast of the Americas and good hunting all of the way south. Waiting for the overland ice-free passage probably brought additional peoples that intermarried but there have been people here a very long time!
The continental shelf must have been exposed, and the temps were, like always, warmer at lower latitudes and lower altitudes. Once underwater archaeology becomes more common — and it makes a nice end-run around the NAGPRA nonsense — all of the limits on the antiquity of humans in the Americas are going to look ridiculous. Of course, that’s just based on what little has been found so far and by the common basic human behaviors. :’)