Megafauna Was the Meat of Choice for South American Hunters

I also don't entirely follow your point that goes from 'backbreaking work' to 'sedentary lifestyle'. The latter only happened in the post war years when we worked out how to have all of the energy we need on tap. Before then, life was hard, albeit not for everyone since we have hierarchies.

It's understandable that ancient hunters might have focused on the larger animals, some of which may also have been less dangerous to hunt, but other smaller animals like deer, bison/cattle, pigs, horses were also common at the time, and even today hunter-gatherer lifestyle seems common among primitive tribes, and agriculture/farming (e.g. Maasai - cattle) less so.

There are other theories for the neolithic revolution and switch from hunter-gatherer to farming lifestyle, including things like population density (partly by cultural choice), and post-ice age climate change enabling farming.

There was no need for complex societies anywhere ever. You can find primitive peoples in pretty much any environment on earth (hot, cold, wet, dry, etc). I think it’s much more likely there were complex societies we never heard of that have vanished over the centuries. 200,000 years is a long time (and that date only goes further back as our understanding increases). How long would it take for remnants of our civilization disappear if an apocalyptic meteor hit?

A complex society or a natural disaster (a la dinosaurs) wiping out megafauna sounds much more plausible than the equivalent of the primitive societies we see today.

"[Men] lived like gods without sorrow of heart, remote and free from toil and grief: miserable age rested not on them; but with legs and arms never failing they made merry with feasting beyond the reach of all devils. When they died, it was as though they were overcome with sleep, and they had all good things; for the fruitful earth unforced bare them fruit abundantly and without stint. They dwelt in ease and peace."

Myths of pre ice age life were spoken of by plato

What, do downvotes mean no? I thought this fitted nicely.

Agriculture, at first, simply made life easier. You didn't have to be nomadic always looking for more food, you could just stay in one place. Your food was right there. It was awesome.

The problem was, it was so insanely successful -- you were having so many more children because of all the food -- populations shot up and suddenly there wasn't enough food anymore when you had a bad year.

So it's actually the opposite of what you're describing -- from what I understand, famine wasn't really a thing until agriculture caused populations to increase massively.

Essentially, it claims that modern humans and our ancestors starting with Homo habilis were primarily carnivores for 2 million years. We moved back to an omnivorous diet starting around 85,000 years ago after killing off the megafauna, is the hypothesis.