I would agree with Blueflame in that the primary purpose is to reproduce. That doesn't stop people having lots of secondary purposes, and in an animal as capable of abstract thought as a human those secondary purposes are able to be assigned greater importance by the person holding them.
If we were flatworms, then yes, if you didn't reproduce you'd be pretty useless, but I like to think we've become more than that At the very least, adding your own experiences and ideas, and otherwise positively affecting the lives of those who do reproduce would acheive the primary purpose.
If we were flatworms, then yes, if you didn't reproduce you'd be pretty useless, but I like to think we've become more than that At the very least, adding your own experiences and ideas, and otherwise positively affecting the lives of those who do reproduce would acheive the primary purpose.