Your point about people being sick is valid, but not to the extent that you think. Firstly, it is not wise to suggest that hunter-gatherers were physically worse off than us. They got a lot of exercise, and were in all likelihood better physically. Secondly, the shorter lifespans statistic is an artifact of increased childhood mortality. Once you discount the child mortality, they had lifespans very similar to ours. Without all the diseases of affluence that we have, mind you (diabetes, for example).
