Why is ancient man more enduring than modern man?

The ancient people were hardy, but did not know about it. Lack of civilization, benefits, tempered man. Nature, climate, an urgent need to find food on his own influenced a person. If our ancestors were not so active, they simply froze to death in caves. There would be no large settlements, no progress. It is more difficult for a modern person, because there are many temptations, and robots do half of the work for them.