"Gregory Nyssen has very properly observed that the superiority of man to all other parts of creation is seen in this, that all other creatures are represented as the effect of God's word, but man is represented as the work of God, according to plan and consideration: Let us make man in our image, after our likeness. See his Works, vol. i., p. 52, c. 3."
God made man to represent Him on earth and to take care of creation. The earth was meant to be the domain of man (Psalm 115:16). This is comparable in certain respects to the ancient Near Eastern idea of statues of kings or deity representing their presence. The object of emphasis was not so much physical appearance as more so one's special rights or privileges. It is in that sense we are made in the image of God.