death rates include the pre-born? I was a late 50’s early sixties kid.
Consider this also. The average lifespan of the colonials included the deaths of children under 5 and many little ones died young. If they took out the kids I bet the life span would not be 45.
https://www.verywellhealth.com/longevity-throughout-history-2224054
I can give you a MUCH more recent example, my father’s family.
If you include only those that were born and lived to adulthood in the 20th century, their average age at death is 82.6 years, but if you include the infant deaths, that average drops to 59.3 years.
THAT is why the “average age at death” in the middle ages was ~34. If you made it past 6 years of age, and avoided industrial death, you lived just as long as today.