I noticed the same thing. I also notice on many web-sites that have pre-historic information also list the temperatures/climates and atmospheric make-up, often significantly different than today or even in recent history.
Most often the temps and humidity are stated to have been much higher and the CO2, as well as other greenhouse gasses, was considerably higher as well.
Gee, and all that plant and animal life was thriving then.
Yes. Not everyone will die off. It just means the planet won’t support as much himan life, as climate bands will shift faster than soil types can keep up. But it’s not a big deal if we accept lots of people dying off and giving up our lifestyle to become more primitive.