yeah man thats the heart of all philosophical discussions, why, why do we exist at all, why are the chemicals released. if there is a god, why is it there. why ask why. I will go one step further.
Whats caused almost everyone in this thread to automatically assume there is a purpose, or that we havent already served our purpose. Right off the bat by submitting an answer you are rejecting the idea that we have no purpose, you are then saying not only do we have a purpose but that you are sure our purpose hasnt been served or fulfilled yet. I find blind obedience to the idea of us waiting to take part in fulfilling some cosmic checklist, ie. divine purpose, that for some reason has not been completed yet, very....wait, we already have 1000 threads on religion and i just realized this is one of them.