Ge 1:1 In the beginning God created the heavens and the earth.
Back in Egypt, the Egyptians worshiped many gods. They had a sky god named Sibu who copulated with the earth goddess Nuit which resulted in the birth of all things. They also worshiped the sun, the moon and the stars, the birds of the air and the animals on the earth.
With just one sweep, Moses here in this verse throws them all away. Everything they worshiped was all created by God. God alone, therefore, must be worshiped. He, after all, was the one who created the universe and everything in it.
The very first verse is to reinforce the command: "You shall have no other gods but Me."