Courtesy of Satoshi Kanazawa in Psychology Today, an illustration of the dangers of averages. The human lifespan is now pretty much what it has always been, around 70-80 years. I have heard it said many, many times that "in [insert era here] you were old when you were 40!".
It is probably true that people were more decrepit in old age, given the afflictions that were then untreatable, but in general the human lifespan has not increased with modern medicine. What has increased is the average number of years a newborn baby can expect to live in a given society in a given time. Childhood diseases used to claim nearly half of all children before modern medicine. But, if you lived past that, you could expect to live to the same age as anyone today.