Threads like these always make me wonder how future archaeologists of a later sentient race would deduce our existence.
Assume it takes >10 M years or so for a new one to evolve once we are gone.
All of our constructions will be long gone, even the pyramids won't last that long.
Some human skeletons might be found, and the relative abundance during an extinction event would at least show we are successful.
But the most telling things would, in my opinion be the fact that there is a rather uniform layer of hydrocarbons (the remnants of our plastics) and metals like gold/iron/aluminium/copper, deposited as our cities decay. This layer will NOT conform element distribution as would be expected by natural means. In fact, they would be found on areas that were clearly mountain less plains, with no plausible mechanism on why these elements would aggregate there.
The fact that we have found no such things suggest that IF an intelligence evolved on earth before us, they never got to metalworking stages. Not even an easily found metal like gold.