with blue eyes, I dont believe it!

were initially thoght to be from Africa, which would have made sense, it's not that long a voyage.

What they found was more astonishing, they were from east Africa,all right, but by way of Melanesia and Australia.

Either there were a lot more islands poking their heads up in the Pacific for island hopping or they were hunters who hunted close to Antarctica and traveled up the east coast of S. America.

While DNA tells us the largest migration was from Siberia through Beringea, it seems clear they didn't find a land mass empty of humans.

As for Neanderthals and Denisovans, they don't seem to have survived beyond the Campanian Ignimbrite Eruption, the one that spread ash from present day Naples into central Siberia and most likely ushered in centuries of intense cold.

ancient fossil footprints and their pathway to South America? I could see in the White Sands footprints some characteristics of Native American foot shapes (I have some of them myself, courtesy of grandma), but would not be able to trace an origin across the globe just from the footprints.

The Campanian eruption lowered global temperatures by 2 to 3 degrees Fahrenheit for about 3 years, AFAIK. The greater problem was acid rain and sulphur and chloride that was dispersed, affecting the entire globe, but especially areas closest to the eruption (southeastern Europe) and along the path of the volcanic cloud into central Russia, north and just a little east of the Caspian Sea.

Homo sapiens survived, so the eruption would not have been the only factor in the demise of Neanderthals and Denisovans, would it?

Very interesting.

If people were already in North America before the Last Glacial Maximum 20,000 years ago, then they might not have had a glacial barrier right up to the Pacific Coast of North America. During the glacial build up, before the glaciers reached their maximum extent, sea levels would have been continually dropping, exposing more land that became Beringia and more Pacific Islands. So instead of following the "kelp highway" at the edge of coastal glaciers, they would have been island hopping down the Pacific Coast of what are now British Columbia, Washington, Oregon, and California.

So good places to look for early people in the Americas would be submerged islands off of the Pacific Coast. Also, along the waterways that empty into the Pacific since people would have followed them inland, south of the glaciers. Some of the ancient waterways might have been cause by glacial melt at the southern edge of the glaciers, and therefore, would no longer exist. So another area to look would be across the US in the regions that would have been a few miles south of the glaciers. They would have, at that time, been good places to live and make camps. The meltwater runoff would have created streams and lakes for plant growth, drawing animals and humans.