All you have to do is to add up the ages on old tombstones. Several members of my family have exceeded 100 years. (My mother celebrates her 100th birthday next week.) But the previous centenarians were around in the ealy 1800s.
When we buried my father in the family plot at the tender age of 56, I noticed tombsones of other famil members, going back 3 generations, who had all lived into their 80s and longer.
Right, old people don’t seem to have been particularly rare back then. In fact, doesn’t the Bible say a typical lifespan is three score and ten years or something? So even back then living to old age was the norm (if you can call 70 old age...my dad turned 70 recently and he can bench press more than I can!).
And hats off to your mother...people who’ve lived life for that long and seen what they’ve seen are a true treasure.