Life expectancy figures are nearly always based on expectancy at birth. But most of the large increase in 'life expectancy' in Western countries over the last 120 years came from the virtual elimination of child mortality. Which means that, if you were to take the figures for life expectancy at, say, age 10 or 15 or even 20, the improvement over the last 120 years would be nowhere near as great as is usually quoted.
There have always been people who lived to a ripe old age (Thomas Hobbes was one: 1588-1679). Just not many of them.