it is a puzzle why the Bible should say 70 or 80 years for the human lifespan. Perhaps the compilers of the Psalms were looking at the optimistic age for death in the text they had-- and it reminded them of Moses long life-- so they attributed Psalm 90 to him? Otherwise they must have just made up the ages to sound impressive. However the Bible's claims in Psalm 90 regarding human longevity, is not backed up by the unremarkable archaeological finds of ancient Canaan.
I think the average and median ages would be skewed by high infant mortality rates, and women dying in childbirth. If you take war, famine and uncommon situations like the plague of 1400’s out of the statistics the ages were probably pretty similar to today.I’ve heard that the ages of hunter gatherers were pretty high. Remember our two biggest killers - heart disease, diabetes and many types cancer predicated on diet and smoke etc would have been virtually unknown. I know cancer existed ( dinosaurs had cancer) and I expect it’s bred into us in terms of mutation driving evolution. But many types of cancer are related to modern lifestyles.
We started getting sick when we became sedentary farmers, living in close proximity with each other and, most importantly, our animals.
If you think about some of the worst recent epidemics they began as cross species diseases(there’s a word for it, slips my mind but It probably begins with Xeno or zoo )
We are healthier taking lots and lots of physical exercise (running!)and not eating too much. I have a belief one veggie meal a day and meat maximum once a week keeps you healthy. Green leafy veg, whole food etc