AI is still very much an unknown factor. Much of the AGI superintelligence doomerism is just anchoring bias around 50s and 60s extrapolations of bad anthropology that thought we were smarter than the Neanderthals and killed them off, so if something smarter than us existed it would try to kill us off. There’s probably much higher odds of symbiosis, but an effectively uncontrollable self-determining disembodied superintelligence is a pretty big unknown, and if I had to put money on it, in almost all cases is going to be quite bad for the worst people in the world.
As for the ancient group, that was mostly just citing the sentiment. But they were pretty neat. Around 2,000 years ago there was a big debate over intelligent design vs evolution (as described in Lucretius) with the latter group claiming death was certain because the soul depends on the body to exist.
So then this group emerges who claims there was an original evolved humanity who had all died out, but that before they did so they brought forth a new lifeform literally made of light, and that this life form was still alive and had recreated the universe and humanity in a non-physical copy where the copy of humanity weren’t dependent on physical form and could continue on past death. They claimed this world was the copy, and that the evidence for this being the case would be in the study of motion and rest, specifically mentioning the ability to find indivisible parts making up matter.
As someone who has been a fan of Nick Bostrom’s simulation hypothesis, I stumbled across this group years ago when exploring a theory that if this world were a simulation, it might have a 4th wall breaking Easter egg in the lore similar to most virtual worlds we have built so far. It’s been a pretty weird few years since as things like AI suddenly went from SciFi to reality with compounding advancements and are trending towards literally being inside light - all in parallel to humanity seemingly continuing on the path towards extinction.
So maybe even if humanity destroys itself, it will simply be the end of one thing and the beginning of another?