The destruction of the Megafauna was an understandable mistake by our ancestors. They then learnt how to compensate for that loss using fire. Here's a nice article on how native Australians did that: https://www.abc.net.au/news/2021-05-11/historic-photos-guide-indigenous-burning-great-sandy-desert/100083720.
Global warming seems to start earlier than one would expect at the start of the Industrial Revolution. Of course a lot of other stuff was going on around the world at that time. One thing was whaling on a huge scale. Well it turns out that whale poo is an important fertiliser in the ocean, and dead whales carry a lot of carbon to the ocean floor. The whales will come back in a few centuries, but meanwhile we need to do their job to get the oceans full of fish again: https://www.nextbigfuture.com/2018/01/iron-fertilization-of-the-ocean-is-as-natural-as-whale-poop-and-it-can-save-the-planet.html.
And as in my previous post (https://grampsgrumps.blogspot.com/2021/04/the-plan-to-revive-mammoth-steppe-to.html), the megafauna were important in sequestering carbon in the Arctic, and replacement is not impossible.
Update: Another great video with stuff I didn't know about humans compensating for problems: https://youtu.be/cfl7mSG13e0. In this case, Thiamine deficiency in wild animals and fish, probably not related to megafauna extinction.