So, humans were camped in Texas at Buttermilk Creek, making stone tools long before they knew how to make Clovis points. The “Clovis first” theory of North American archeology is now shown to be wrong, after 80 years’ dominance. Kudos to the Baylor and A&M teams, among others, who found and “pedigreed” this very important site.
The Buttermilk Creek thing is no real surprise to me and a few others. There have been reports on this topic published and debated in AAAS's peer-reviewed journal "Science" for some years now. Some of these mention other sites in way-far-south South America, some deemed as old as 26,000 years. Not everyone agrees with those dating claims, although the youngest reported date for that South American site still predates Clovis. The persistence of these not-yet-accepted reports tells me that humans settled the Americas long before the Clovis folks, probably during the height of the last ice age, if not before that.
My sort-of-educated guess is that they traveled along the coastlines by boat, living off the sea by fishing, sealing, and whaling. The remains of their camps are probably buried in the sediments deep beneath the sea, since sea levels during the ice age were as much as 480 feet lower than they are today. These sites would be widely scattered and almost impossible to find, excepting the wildest strokes of luck. (I've seen geological reports in that same journal about fossil beaches that far below sea level, and as high as 350 feet above sea level, which explains why the current evident polar ice melting trends alarm me so.)
Seeing as how the concrete and steel we use today won't reliably last 5000 years as archeological evidence, then what does constitute believable evidence of an advanced civilization (human or not) tens or hundreds or even thousands of millennia ago? As a result, we simply do not know whether our ice age ancestors were sophisticated folks with an advanced civilization of some sort.
Nor do we know that they were not!! If they had built houses and sailing ships of wood and plant fiber, how would we know? Those kinds of artifacts simply do not survive very long. Many folks who should know better have never actually faced up to that question.
And a very interesting question it is.