Well, that and survive yourself through said childbirths, which was (and indeed is) never guaranteed for approximately half of humanity. Childbirth is dangerous! Obviously, humans have always had more than enough children on average, but the burden of it is quite high.

It does, but the parent poster who lives in a van does not do it, and therefore he's not really surviving anything. And as the first reply to the van implied, he would not be boasting "spiritually" if he had to deal with children in his van.

Everything works as long as you discount survivorship bias.

The species can survive this way. Individuals - not really.

If the species is also alive, that means individuals are alive.