Carrying on with the thought @_Whitetigress expressed about the universe: we exist because life took hold somehow on this planet out in the boondocks of the vast Milky Way Galaxy. And once life takes hold, the survival of the fittest begins; and ultimately, an alpha predator results. We are that alpha predator. We eat Orcas.
What is our purpose now that we exist? Well, aside from feeding ourselves and reproducing so we continue to exist and evolve, it is to ask why. It is to explore. Why must we put a man on Mars? Why then figure out how to sail out past the Ort belt and explore distant exoplanets that are habitable? Because that’s what we do. Humans have always asked “Why?” and “Why not?”. We have always explored. And if we do it long enough, we will someday learn why we exist—why abiogenesis happens.
If there is an intelligence that rules it all, we will meet that intelligence someday on equal terms. And in that day, if there is no such intelligence, we will become it. And whichever the outcome, that’s reason enough to exist.