People longevity. How long people used to live before

It is a video about how many years people used to live before.
We know for a fact that they used to have lots of children before: 5, 7 or even 11 children.
Now I have a question for you: why they were having so many children if they were dying very young: at 30 or 40?
Who was raising their children? They were having lots of children, so they will abandon them later on? This does not really make sense to me.

No, they were actually living much, much longer than we do.