You can retire at any age—you just need the money to do so. But if you think you can live off of your Social Security monthly check alone, you’re dreaming. It was always “supplemental income”, not designed to provide one with a life of leisure by itself.
For perspective, consider the reason 65 was chosen in the 1930s when Social Security was first established is because at the time the average life expectancy for Americans was 64. Given that it’s now (depending on the sources you read) somewhere between 75-80, that would mean that if the Social Security benefit eligibility age had “kept pace” is would be something in that range.
It’s less about life expectancy and more about the ability to work. Many physical ly demanding jobs are pretty much impossible even in your early sixties. And at 70, many people are not mentally capable for a job much more demanding than a Walmart greeter.
Plus, most of the gains in life expectancy come from reductions in infant mortality. Actual human lifespan has barely changed at all. In all likelihood, your person who died at 80 in 1940 would probably live to be 80.5 today, and that extra six months would be enduring the hell of chemotherapy while the medical industry drains his kids’ inheritance.