Nothing is proved because it cannot be disproved, strictly speaking. But there is an awful lot of scientific thought that rests solely on that premise and has strong consensus.
That gets back to my point about us all having our own level of proof, based on what we reject as statistically impossible. e.g. what we will reject and accept as having to have been made by men. A better example than the fantastic ones I've tossed out is the case of flint tools. Anthropologists are constantly arguing about particular chipped rocks and as to whether they are natural or shaped by humans. They can't prove it either way.
Can you expound on that? I'm not aware of any "scientific thought" that rests solely on that premise, and absent any supporting objective evidence.