It only makes sense that life has existed before us.
I still have the idea that this is not the 'first earth' that has existed by a long shot.

Maybe this planet existed before the big bang, maybe that civilization was destroyed by a doomsday event, and formed this earth, or something.

I know it doesn't have much sense, but yeah, it's some weird idea I have been having for the last couple of years, I intended to write an story about it or something.