Back around 1900 people didn’t live long enough to die from cancer. Women died at a young age in childbirth, children from childhood diseases, many from infections before the discovery of antibiotics, etc., and lots of medical events and complications that people these days now survive. Heck, back then strep throat could be a death sentence.
I used to think the same thing but read that it was the deaths of kids that brought the “average” lifespan down. Check the numbers again.