The Bible addresses the creation, fall and restoration of humanity.
God’s relation with and alien race could be alien to us.
Aside from that, ever wonder about the whole back story of angels?
Completely agree. Alien to us could mean anything at all, including the possibility that we cannot even see them except when they (or God) choose to reveal themselves. God is infinite, infinitely good and can and will do what he chooses. Through Christ we have the privilege of witnessing that for eternity.