Since God took the form of a man in the person of the preincarnate Jesus Christ this has to mean that Jesus Christ is God. So on what basis do I come to this conclusion? On the basis of what Jesus Christ Himself said at John 6:46, "Not that any man hath seen the Father, except he who is from God, he hath seen the Father." And on the basis of the testimony of Old Testament saints themselves. Look at Genesis 16:13, "Then she/Hagar called the name OF THE LORD ( YHWH)WHO spoke to her, Thou art a God who sees; for she said, Have I even remained alive here after seeing Him."
Look also at Genesis 18 reading the whole chapter. Here is what vs1 states, "Now the Lord (YHWH)appeared to him by the oaks of Mamre, while he/Abraham was sitting at the tent door in the heat of the day." Please read the rest of the chapter and cross reference what Genesis 21:2 says regarding Genesis 18. "So Sarah conceived and bore a son to Abraham in his old age, at the appointed time OF WHICH GOD HAD SPOKEN TO HIM."
And who appeared to Isaac at Genesis 26:2? "And the Lord appeared to him and said, "Do not go down to Egypt, stay in the land of which I shall tell you." Now look at Genesis 26:3, "Sojourn in this land and I will be with you and bless you, for to your and to your descendants I will give all these lands, and I will ESTABLISH THE OATH WHICH I SWORE (YHWH)TO YOUR FATHER ABRAHAM."
Where did God swear this oath to Abraham ? Look at the whole chapter of Genesis 22 specifically verses 11-18. It was the angel of the Lord/Jesus Christ who swore the oath and He is identified as, what did you say, "God introduced Himself in the first person singular as "The Being." In fact, even the New Testament backs up this first person singular being swearing the oath by Himself at Hebrews 6:13,14, "For when GOD made the promise to Abraham, SINCE HE COULD NOT SWEAR BY NO ONE GREATER, HE SWORE BY HIMSELF. saying, "I will surely bless you; and I will surely multiply you." If you believe that it was an angel that swore the oath on Gods behalf than why does the text say God swore the oath BY HIMSELF AND THERE IS NO ONE GREATER, especially created angels?
hope this helps !!!