The things we leave in space are the final proves that we ever existed. Especially the interstellar probes, the Voyagers, Pioneers, New Horizons. They will outlive us, our civilizations and our existence. I think I said that in the original post. Greenhouse gases and extinction events don't require human intervention. I think this ought to be a little more than suspicious though. To quote Isaac Arthur , "aliens mistaking a hammer for a natural formation could be excused but an entire workshop ought to raise alarm."
