God created human beings as the summit and apex of all creation not only giving us our physical bodies and natural life but imbuing within us an eternal soul so that we can be in relationship with God now and forever. In doing so, God was preparing the world for the greatest gift of salvation which is the sending of his Son, Jesus, who became truly human and dwelt among us.
Ultimately, God creates humans out of love with the desire that we will love the Creator in return.
As I express that basic tenet of Christian faith, I want to quote Thomas Aquinas, “For those who believe, no explanation is necessary. For those who do not believe, no explanation is possible.” Thomas’ statement does not dismiss the many sound arguments in favor of God’s creative action, but rather points out the futility of such approaches for convincing a nonbeliever.