As a registered geriatrician I keep tabs on the tools of my trade particularly its language. In this regard I draw attention to the two phrases "life expectancy" and "life span." In my reading in the domain of aging these two are often casually misused, leading to confused conclusions. They are often presumed to be interchangeable, which they are not. Life expectancy and lifespan should, could be synonymous. In the ideal world we would all live to our maximum of 120 years, but the real world reveals a very different scenario.
Let's look at dogs for example. The Guinness Book of Records reports that the oldest dog that was verified was a cattle dog who lived to be almost 30 (and herded almost to the end). My and your experience with dogs is far lower, maybe 12 if we're lucky.