We might be pure eternal consciousness.
If we are consciousness, it could be that our purpose in life is to allow our immeasurable selves (consciousness) a biological manner with which to partake in this physical matterium. To be a conduit, through which eternity can presently and currently observe its own imagination, so that we can observe the difference between happy and sad, hot and cold, long and short.
Individually, maybe our purpose is to preside over an alchemical wedding in our brains; blue and red, side by side up the lane and into that piney chapel in the center of the skull. Being given the left brain's math and the right brain's art, it is in these moments- here and now- that we are in charge of the music for this ceremony. Our purpose, then, is to snap our fingers, tap our toes, and get this party started!