We give ourselves purpose.
The only 'real' purpose in life is to procreate.
I understand how scare quotes work yet I can't make out what work they're doing in your second sentence, unless you're using the word
real in its metaphorical gene's-eye-view sense.
Either last night or the night before there was one of those cheap and cheerless documentaries (Channel 5 is the usual culprit for this sort of tat) about a woman who has had (IIRC) 12 children and who has done so while living on benefits. I didn't see the programme, only read the description; as far as I can make out this seems to be the beginning and end of any reason why she should have her 60 minutes including ad breaks in the public spotlight.
Meanwhile, Michelangelo, Leonardo, Newton, Beethoven, Nietzsche, Van Gogh and innumerable others died childless. I'm not saying that there's some sort of objective, external standard of the pointfulness or pointlessness of a human life (exactly the opposite, actually); but I am saying that, given the fact that you're only ever one generation away from the end of your genetic line (i.e. you may produce children who do not themselves reproduce), the capacity for having children seems a thin rationale on which to hang the point/meaning/purpose of a life.