I think there are many people who wonder about their purpose in life...but from reading the Bible, I get the distinct impression that the collective purpose of humankind is to act as caretakers and custodians of this planet and the creatures who share it.....and we are doing a terrible job! Are we accountable? I believe we are.
Individually we can fit into that collective purpose by being the kind of humans who will do as the Creator instructed so that life can be the joyful experience he intended it to be....not the nightmare it became when humans abused their free will and started imposing their will on others. That is why power corrupts people....we were never supposed to tell others what to do...to wield authority over them.....we are designed to have God tell us what to do, like a loving parent instructs his children.....and therein lies the reason why we can never get our act together....no one it seems is interested in having God tell them anything. It would be a very different world if we could learn to love, half as well as we can hate.
ETA.....Are you a believer? You just answered that...