There are as many answers to this question as pages in this library, but they basically fall into two categories: teleological (related to purpose), or etiological (related to causes & origins). The first asks What is our purpose? and the second asks What caused us to be? Some might add a third category: phenomenological (related to experiences), which asks What is happening? You could do worse than to explore all three (teleology, etiology, and phenomenology) in the Stanford Encyclopedia of Philosophy: https://plato.stanford.edu. Me, I think we’re here to love.