Plastics either.

Oh, no, plastics will unless deliberately burnt, and it'd take most of our species's resources to go out and find all the plastic and get rid of it in a lifetime. The rest of your points are good, though.

Your point about the Ice Age glaciers is especially good, too. Given this new information, I can update my estimate (after looking up the Bayesian formula and how to use it, because stupid old me hasn't memorised that yet) Bayes' Theorem is not useful here.

I've upped my 0.1% to 2%; 1 in 50 chance that the vast, vast majority of the evidence was either wiped out, buried by subduction, dismantled by other humans or otherwise rendered unreachable to us. Because your "human destruction" and "glacier" hypotheses are things that I hadn't thought of, and taking that into account makes it conceivable that such a thing might've happened in a hypothetical world (glaciers trashed loads and loads of evidence, and humans who didn't like it cleaned up the rest, so the hypothetical civilisation wouldn't have to have been so unsimilar to my expectations of how humans behave).

That makes 0.000018714%. It's still not really worth considering.