It skewed short because of high infant mortality, up until about a hundred years ago. I have a copy of a great aunt’s genealogy record. Dates back to our earliest ancestors here in the US. Men have been living to their mid80s, women until their mid90s since the 17th century.
What’s different is the number of kids who survive childhood. As recently as my gr a parents generation, half the kids didn’t make it to adultnood. Throw in safe that cut you g men down in their prime, that stunts life expectancy figures too, unless statistically adjusted for.
What you say is true. A person’s expected age of death was quite different at birth from what it was if the person survived to, say, 40.