In the OT there are two Gods. First the God who is not seen, because he is spirit, and second the God who is seen, because he is the manifestation of the invisible God, who is called "angel". He speaks as if he were God because he is God, but at the same time there is another God who sent him. Both work together, they work as one.
The Angel of the Lord in OT is Jesus! When Jesus was born that Angel disapeared, because he is that Angel! The Angel of the Lord is the Word of God, everything was created through him.
Jesus isn't a created being, he is the Word of God. The Word of God cannot be created. It sounds illogical to us human beings, but God's word is a person, we cannot compare our word with God's.
That's my thought.
In the early books of the Tanakh, henotheism is the norm and Yahweh is one of many tribal gods ─ see Exodus 15:11, 20:3, Deuteronomy 5:7, Numbers 33:4, Judges 11;23-24, Psalms 82:1, 86:8, 95:3, 135:5 &c. The example from Judges is particularly clear:
Judges 11:23 So the Lord, the God of Israel, dispossessed the Amorites from before his people Israel; and are you to take possession of them? 24 Will you not possess what Chemosh your god gives you to possess? And all that the Lord our God has dispossessed before us, we will possess.
And that's also why the commandment reads "no other gods before me", not "ain't no other gods".
But by the end of the Babylonian captivity, monotheism has taken over. In this monotheism, God has two principal forms (apart from burning bushes &c) ─ as the invisible almighty God of the Jews, and as the
ruach or breath of God, which resembles the Holy Ghost but is not a distinct entity but simply a form of the only God.