I am the LORD your God, who has brought you out of the land of Egypt, out of the house of bondage. You shall have no other gods before Me.
The Suzerain establishes His position by noting He redeemed the vassal nation from abject slavery. They were booty, a military prize by right of conquest. There was no room for disputing whether their new situation was any better, as they went from nearly untouchable status below a pagan and evil people, to a liberty as their own nation.
No other authority on earth had any claim on them.
All previous allegiances were broken. Any attempt to develop a rival dependency was more than simply ingratitude, it was a return to slavery. Further, there was the assumption it would be high adultery. Conquering rulers of the Ancient Near East always married their vassals to themselves, unless their aim was to dissolve a nation into slavery. This was a reversal, a promotion to nationhood and prominence — from death to life. This deity had not simply claimed them as His own, but humbled a whole pantheon of rival pagan deities in the process.
By every measure any human would understand in those days, the slightest deviation from allegiance to Jehovah was a grave and fatal error. Every single one of the adult men in this nation understood this personally, as they would have reacted severely had their newly purchased servant, taken from the most degrading situation and given a high social prominence as steward, began serving any other master. Any man would have reacted with extreme anger, fully justified, if his new bride was unfaithful.
This was intensely personal. God does not simply claim some measure of performance, or some portion of assets, but the whole person. The very breath of life was subject to His whims, and by extension, the very soul.
It is the norm in Hebrew literature we should attempt to read between the lines. It was not simply taken for granted, but expected, demanded. The symbolism is obvious: God owns all Creation. Not just Israel, but every human on earth — if it breathes, He owns it. He might excuse a certain amount of confusion regarding what was required, but not the basic assumption allegiance is due Him. There is absolutely no grounds for denying, quibbling or cutting corners on this. By extension, we find here the concrete reality which is symbolic of what Christ did on the Cross. Mount Sinai was merely about the Hebrew nation, but Christ died for all humanity. This is not simply a fresh permit to approach God through Him, but a duty and command to approach Him.
Nor does it matter if any of it makes sense to you. Your failure to grasp the nature of this was simply your problem, and could not relieve you of any obligation to offer full and heart-felt loyalty. No earthly power can lay any claim to that which He says is His. No other presumed divinity, no demon or angel, nor any imagined absence of the supernatural, is permitted to claim any portion of your unreserved loyalty.