Human lifespans have not changed over the millennia:
People in the past were not all dead by 30. Ancient documents confirm this. In the 24th century B.C., the Egyptian Vizier Ptahhotep wrote verses about the disintegrations of old age. The ancient Greeks classed old age among the divine curses, and their tombstones attest to survival well past 80 years. Ancient artworks and figurines also depict elderly people: stooped, flabby, wrinkled.
Hunter-gatherers today have a normal lifespan of about 70 years too, of course, but hardships reduce the likelihood that a given person will reach that age.
The maximum human lifespan (approximately 125 years) has barely changed since we arrived. It is estimated that if the three main causes of death in old age today—cardiovascular disease, stroke, and cancer—were eliminated, the developed world would see only a 15-year increase in life expectancy. While an individual living to 125 in the distant past would have been extremely rare, it was possible. Christine Cave, “Did Ancient People Die Young?” at Sapiens
This matter is worth clarifying because people arguing dubious claims about the mindset of ancient man sometimes assume that few people were around much beyond thirty years of age. But enough of them were around that the lifespan of 70 to 80 years was accepted as the norm for a human being, irrespective of the percentage of the population that reached it.
See also: Is aging a “disease” or does it have an “evolutionary purpose”?
Study: Religiously affiliated people lived “9.45 and 5.64 years longer…”
and
Anomaly: Human mortality hits a plateau after 105 years of age From Discover Magazine: “ That is, you aren’t any more likely to die at 110 than at 105. It’s a contradictory finding, because mortality ticks steadily upward as we get older at all previous ages.”