Bible scholars tell us that this part of Genesis was edited by theologians after the exile. In part, it is an assertion that the God of Israel is superior to the deities worshipped by the Babylonians. And it is an assurance that this God we worship is God who cares for the earth and all the creatures on it. Although God had allowed the exile, God could be trusted to restore the community on its return. (with thanks to Allen & Williamson's Preaching the Old Testament.
Into chaos comes the word of God.
God speaks, and light overcomes darkness.
God enters the world and brings order to it.