I really think you have some mythical view on how people used to live.
Regardless of how far back you go life was harsh, miserable and unforgiving and the further you go the worse it gets.
Fresh food was never a staple diet, hunting wasn’t done on a daily basis it was seasonal meat would be smoked and salted to be preserved.
Fat would be fermented and preserved.
Plants as well would be fermented or dried to be preserved for later consumption.
Famine and starvation was abound whole populations were wiped out due to famine multiple times even before we started to live in large cities.
Living in caves and huts burning wood would result in lung damage even before counting things like cavers lung.
The smallest of injuries could be fatal and it often was.
There was essentially no period in which we were healthier than we are today even if you are an alcoholic coal miner who’s living only on KFC.