Depends on what you really mean by serving a purpose. Nothing has a purpose not really. I have a kid admittedly she does not have the best life but no one does. Its purpose depends on the person to me, to be honest at first it really was an, oh okay let's have a kid now I have grown to like her and am almost a full-time father. The purpose of her existence hard to answer. I have Alexithymia so it is hard to answer much in this regard. I can answer the big questions mostly but these are always fun to toy with.

I have a similar questions. I personally don't what kids of my own, I would much rather adopt a child or just help the children who are already here. the world is a hard place to live an understand, it is not all suffering, but it is hard. I believe that my best or most influential purpose in life would be to help the ones already here. if that makes any since.

It's a great ego boast

its natural to want your genes to carry on but its a terrible idea as there are way too many humans taking way too much.