The idea that there was one window of time available for the single Precolumbian peopling of the Americas persists, but is outmoded. Its defenders are dug in, but are getting older and older and will die off.
The Clovis-first-and-only model is, alas, getting superseded by the “anti-colonization” idealogy, which is inherently and irreparably antiscientific.
Humans didn’t move eight miles per generation, they were all the way down to Tierra del Fuego at basically the same time that the oldest cultural remains in Alaska. The strait wasn’t an impediment to migration (in the right time of the year, of course) and any folklore-driven culture would know the ancestors had crossed over from Asia, or had waved goodbye to the relatives as they migrated to the Americas.
I tend to give James Michener’s sources some credit.
Your last paragraph makes no sense.
Read it again and rewrite what you hope to be sense.
Yes, Tierra del Fuego is at the Southern tip of South America.