Racist question: would these be the ancestors of today’s Native Americans, or previous groups (e.g. Clovis Man) who predated the present tribes?
There is no evidence that of any people not related to present groups. Clovis, Kennewick etc. are related to modern Native Americans.
They would be ancestors of today’s. There’s no evidence that they were exterminated by some unknown group. Later cultures like those who built the mounds at Cahokia also used copper and made some fine copper artifacts- copper-covered ear spools, embossed copper plates, copper-covered box turtle shells, pressure flaking tools for working chert, etc. They traded for copper from the Great Lakes region, then fashioned the metal into art, and exported it for other items from afar, like micah, obsidian, and whelk shells.