Cataclysmically:
To wipe us completely, our biggest currect threat is Texans with nukes. They are the craziest people around with access to world ending nukes.

Then comes disease, however with the number of people and the tech we have there will be peeps resistant to just about anything. And our tech means we will probably cure whatever it is before it kills us all.

The most eventual methods of extinction of humanity on earth are super volcanos and comets. But these aren’t necessarily immediate threats. Hopefully we are interstellar by then.

Global warming and our raping of the environment won’t lead to globan extinction of humanity. If could lead to chaos where super weapons, nuclear and biological, are more commonly used. But it is the weapons doing the extinction, not the environment.

Like ‘iron age or earlier’ rudimentary.

I think first there’ll be some major waves of homo sapiens herd-thinning achieved by global warming, various nasty germs, “diseases of civilization,” etc. And then some waves of resurgence, probably among folks like the Andaman Islanders since the people most removed from modernity are probably best equipped to survive such events.

To knock us out completely, it’ll undoubtedly take either a) being displaced and made obsolete by a new, improved homo species, like on that short-lived, flawed but still interesting TV show Prey or b) suffering a Bruckheimeresque planetary cataclysm.

Either that or many reincarnated passenger pigeons with guns.