But mammoths existed for thousands of years, the Clovis people showed up, We have found Clovis points in mammoth butts, then we find no more mammoths.
Did the Clovis people cause or contribute to the extinction of the mammoth?
We will never know.
But there is an obvious pattern of humans showing up, and lots of mega-fauna going extinct.
The evidence of that is hard to deny.
According to those who worship Mother Gaia in the O-So-Green-Movements. this was a great tragedy. They will make it go the other way 'round, next time.
We learn more and more about the past every year. New ways of interpreting old evidence are continually being developed. Consider the plate tectonics revolution. Geological processes we now take for granted were laughed at prior to the 1960s. We now have a whole new and insightful way of looking at the Earth's past.
I think the megafauna extinction mystery will eventually be solved. My hunch is catastrophism of some sort or climate change or both, but my evidence is as sketchy as yours. I sincerely doubt small roving bands of stone-age hunters could push so many species into total extinction unless they were already hanging by a thread for some other reason. It's just as logical to consider that climate conditions that made human expansion into new areas possible were also somehow responsible for the extinctions.