He obviously had the power to create it in an instant, but he chose to create it in natural progressive steps. God created by his word. He spoke and it was. They see living things as a kind of emanation from God, a part of his being. The Bible says that all three persons of the Trinity, Father, Son and Holy Spirit, were involved in the act of creation.
Animals are a secondary creation, although like humanity, are created out of the dust of the earth.
Yet we do need to remember that the earth and the animal kingdom are created as an environment for us. So although God's creation begins with matter, his intention begins with us. Mankind is the apex of creation, having a single origin and made in the image of God. This means it turned out the way he wanted it. The Bible, in a very simple and unscientific way, answers the fundamental question we have concerning our environment.