We also wouldn't have very much environmental pollution without automation. Humanity wouldn't have left much of a permanent mark on the Earth if we had gone extinct before industrialization.
Barring the desertification of the Fertile Crescent (arguably natural climate change had a hand too) and the extinction of the American and Australian megafauna, both of which are relatively insignificant in geological time, we simply didn't have the means to harm the environment very much.
Compared to that, industrialization has had side-effects that will endure for millions of years: the upending of the carbon and nitrogen cycles, and the addition of plastics and radiation. Aliens could come to the Earth 20 million years after we go extinct, and still be able to find traces of us.
