For the majority of the homo sapiens' history we were hunter-gatherers and were doing fine because that is how we were designed by nature. Because our population didn't spiral out of control or was at least tempered by the amount of food, our hunting and gathering didn't throw whole ecosystems out of balance. Small communities offered close relationships that are rare to find now in our multi-million strong cities. Hard conditions permitted for only the most fit to survive so there was no need for extreme medical intervention.
I find this whole narrative parallels how when people who grow tired of cities and go into the forest to try out that lifestyle at first completely disregard, say, the Native American's techniques to build houses and try to build cottages until a tree almost kills them when it barberchairs and even if they do manage to build something that resembles what they're used to they have to abandon it quickly because it's just hard to build and maintain, doesn't go well with fire and so on. Then over trial-and-error they eventually come back to the original Native American design because it was tried for millennia and can't be improved any further.
So this very much reminds me how now everyone says how sitting is bad for you - yeah, no wonder. Or how the obesity sky-rocketed when some unscrupulous or ill-advised agencies decided to recommend that ridiculous amount of carbohydrates and sugars aren't bad for you, but fats are. The physique and athletic ability that so many people strive for by going to the gym was effortless for hunter-gatherers because they didn't overeat and physical activity were a part of their daily life(not to say that hunting all day is effortless, just the physique came as a by-product of surviving).
Of course, our population has grown much too large for everyone to go into the forests, so we've kind of screwed ourselves already by burning that bridge, however I think we can at least steer humanity in the right direction by looking at where we came from and trying to chart our future path using that.