We exist because of an extremely improbable series of accidents. There's no great reason for our existence.
we exist because natural selection has assured that atoms are able to come together in such as a way as to keep bizarre combinations of molecules inside our bodies and defeat the law of equilibrium.
we know how we exist but no one ever cares about the how, it is the why which we are always concerned with, probably because we will never know. i'd stop looking for why's i and just accept everything as is. perhaps there is no reason why we exist we just do, perhaps not
perhaps we exist to transport water??? or are we messengers of memory??? the human expirence is just that, an expirience...imo