> I'd be living mostly outside, shivering, wondering if I could get enough food to live through the winter
I'm not particularly well-versed on hunter-gatherer societies in this regard, especially in Paleolithic societies rather than those that persisted to the modern day. But given that hunter-gatherers were generally nomadic and had a much more diverse source of foods than settled agriculturalists, you probably would have worried less about food lasting you through winter than if you had been in any agricultural civilization up until 100 years ago or so.
> would have little hope of living past 40
Lolnope. Hunter-gatherer societies had longer lifespans than sedentary agriculturists, and even the shortest-lived societies generally had life expectancies of over 50 years of age if you made it past 5 or so.
> I'd suffer from routine episodes of famine, backbreaking labor,
Once again, hunter-gatherers are probably more resistant to famine than settled agriculturalists. It is now well-known that hunter-gatherers spent very little time working: about 2-4 hours per day of work was required, far less even than modern society.
> and the tribe booting me out to die when I was no longer carrying my weight.
Probably not. Old people hold valuable knowledge, such as which foods are edible in extreme famine.
> I'd watch most of my children die young, and would fear all sorts of stupid mythical boogeymen.
Fewer on both accounts than you would in early settled agricultural societies.
While it used to be thought that agriculture was obviously superior to hunter-gatherer societies (not least because it was independently developed at least 9 times), more recent anthropological work has shown that on nearly every metric, hunter-gatherer societies outperform agricultural societies until about the 19th century.