I spotted this doing genealogy, as well.
My mum died aged 47. As did her mum. So you'd assume her direct line ancestors, farmers in all the villages round here right back to first page of many parish records here, were also shortlived. Because all her ancestors were concentrated in one part of Yorkshire, with the occasional foray maybe in another bit of Yorkshire, they were easy to trace in parish records (where burials sometimes give you cause of death, pre 1837 and certification).
But get back even just into the 19thC and there will be entire families born of 10 or more kids, in these farming families where every single one lives into their 80s... Every single person. And no infant deaths at all. Or one or two per generation. And seen this repeated across various branches of the family. In other words, my 20thC ancestors had lives almost only half as long as many of their ancestors.
You hear a lot about infant mortality but it's only really striking in parish records when there's say, an epidemic like smallpox, or whooping cough. Or in poorer families, sadly - the one line in my mum's immediate past who were labourers not farmers, had most of their kids die before age 2 or 3. But that was so unusual in the genealogy as to stand out.
Swathes of the population were less or unaffected by it. (I'm thinking rural parishes here - cities would be very different but of course pre Industrial Rev most people's ancestors are on the land).
Was at Vindolanda this week where they have an obscene number of Roman shoes - mainly discarded singletons. And it struck me how most looked like a modern size 5 or 6. Some, bigger. I always avoid that cliché when doing Living History about people being shorter in the past, as well. A lot might depend on nutrition and that wasn't always as bad as we'd imagine, for people in say the 18thC or 19thC.
Your life expectancy in a 19thC industrial city might be very short indeed. At the same date, your life expectancy in the countryside might be into your 80s.
A few years back I researched an 1830s' accident which had 3 survivors - all middle aged men, all working class - farm labourers. All three of the survivors lived well into their 80s.