Humans might indeed cause one or more large extinction events, but there are also several known causes (and perhaps many more unknown ones we could discover) of

Humans might indeed cause one or more large extinction events, but there are also several known causes (and perhaps many more unknown ones we could discover) of large extinction events which seem to be unpreventable except through the actions of humans (or another intelligent and technological species). If you were to permanently halt all technological progress now, or perhaps revert to before nuclear weapons or even before the industrial revolution, you could prevent extinction events from, say, human-caused climate change, nuclear war, or Skynet. But you'd also effectively guarantee some other eventual extinction event, perhaps from an asteroid impact, a supernova, or any number of phenomena we haven't even discovered yet.