One explanation is that the Decalogue is – as the Hebrew aseret hadib’rot makes clear – ten statements or principles, not necessarily ten commands.
If, however, the ten are counted as mitzvot there still is a way of understanding Number 1 as a command – “I am to be the Lord your God”.
The true significance of that interpretation is suggested by a Chassidic saying in the name of the Rabbi of Kovrin.
He looks at the words of Moses in Deut. 5:5, “I stood between the Lord and you at that time”, referring to the people’s reluctance to hear the voice of God, and their clamour for Moses, not God, to speak to them.
Says the Rabbi of Kovrin, what often stands between God and us is the “I”, the anochi, the human ego.
When we boast and say, “I am great, I am powerful, I am clever”, we are posing one “I” against another. We can’t both be “I”. The Decalogue says, “The Divine ‘I’ must be your God, not the human one…”