In the beginning, God spoke, and the world was created. His Word alone created the world we live in to this day. After creating the world, God created man and woman in His image (Genesis 1:27). He created us to resemble Him, to do the things He does. As His image-bearers, we have the power of God in our lives to do the things that He does.
We are creative because God first created. We exist because God exists. If God would somehow cease to exist, all of His creation would disappear as well. In the same way that God spoke and created the world, our words create worlds as well. The words we speak define the world around us.