If it wasn’t in the past, I imagine it will be in the future with how common two working parents is now. We want more kids but we are getting zero grandparent help
You only have to live to your 40s to become a grandparent in natural conditions, and your chances of living to at least your 50s have always been pretty good conditional on living long enough to reproduce at all.
Medieval burial grounds, when examined by anthropologists, do contain some people over 60, but the majority of adults buried there died earlier, typically in the 45-55 bracket.
It wasn't just disease, but also wars and famines. And in women, deaths during childbirth, which cluster in the 20-35 bracket.
Cardinals of the Church, who led peaceful lives, didn't give birth and never went hungry, lived into their late 60s and early 70s even during the Middle Ages. But an average peasant wouldn't.
Probably improved more with lots of siblings from a wide age range. The bigger siblings would do productive work, the younger would take care of the little ones.
The problem there is with your definition of grandfather. Currently, the age for a grandfather in developed countries is 55+. For most of humanity's history, if there were grandfathers, they would barely make it to 55 years of age.
