You are paraphrasing the first and second commandments here, not just the first. In the first commandment Jehovah says "I am YOUR God". He does not say He is the only god. His second commandment to them is to have no other gods (plural) before Him. The 10 commandments actually recognizes the existence of other gods. The Hebrews just can't worship them. Exodus also mentions gods of the Egyptians. They are claimed to be less powerful, but it never says they don't exist.
Oh, I have been taken to task on this in a private letter. Back to Dennis Prager’s class on the ten commandments.
There is only ONE God and to believe otherwise is to put your soul in mortal danger.