It gives a true, but partial, view of human nature. Theology can go beyond philosophy and draw conclusions about reality and human nature based on revelation and faith. God has revealed that human beings fully flourish only in relation to an eternal, intimate relationship with God through Jesus Christ. This supernatural calling outstrips natural human capacities and is a gift of grace infused into human nature by God. Although philosophy and theology are distinct for Aquinas, they are not disjoint.
Some truths are a part of both subjects.
According to Aquinas, this is true of the existence of God. Aquinas thinks that unaided human reason can be employed to demonstrate the existence of God. He does this, famously, in his Five Ways. Several of these arguments owe a large debt to Aristotle. While unaided reason can prove God's existence, God has also chosen to reveal this truth in other ways.