There are some passages in the OT that speak about Christ... the messianic passages.
Jesus didn't say that all the OT was about Him. Please examine the verses you have quoted.
Again, if I am misundertanding you, please let me know.
If all the OT were about Jesus, then, was Jesus introducing to the people a new God when He talked about the Father?
Who was the Father, then? Why didn't Jesus have to explain who The Father was?
Jesus quoted the Torah normally, as any Hebrew, and spoke about the God of Israel in third person.
Furthermore, Jesus was clear that the God that his Jewish apostles believing in was also His God.
If the OT was about Jesus, what is the role of the Father in the OT?
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 WHO spoke to her, Thou art a God who sees; for she said, Have I even remained alive here after seeing Him." Genesis 18 reading the whole chapter. Here is what vs1 states, "Now the Lord 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 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 angels who are created like the rest of us mere humans.
The angel of the Lord who is YHWH is worshiped as YHWH- the Lord God !
Gen 22:11-14
But the angel of the Lord called out to him from heaven, "Abraham! Abraham!"
"Here I am," he replied.
12 "Do not lay a hand on the boy," he said. "Do not do anything to him. Now I know that you fear God, because you have not withheld from me your son, your only son."
13 Abraham looked up and there in a thicket he saw a ram caught by its horns. He went over and took the ram and sacrificed it as a burnt offering instead of his son.
14 So Abraham called that place The Lord Will Provide. And to this day it is said, "On the mountain of the Lord it will be provided."
Exodus 3:2, 5
And the angel of the LORD appeared unto him in a flame of fire out of the midst of a bush: and he looked, and, behold, the bush burned with fire, and the bush was not consumed…And he said, Draw not nigh thither: put off thy shoes from off thy feet, for the place whereon thou standest is holy ground.”
Judg 6:11-28
The angel of the Lord came and sat down under the oak in Ophrah that belonged to Joash the Abiezrite, where his son Gideon was threshing wheat in a winepress to keep it from the Midianites.
12 When the angel of the Lord appeared to Gideon, he said, "The Lord is with you, mighty warrior."
13 "But sir," Gideon replied, "if the Lord is with us, why has all this happened to us? Where are all his wonders that our fathers told us about when they said, 'Did not the Lord bring us up out of Egypt? But now the Lord has abandoned us and put us into the hand of Midian."
14 The Lord turned to him and said, "Go in the strength you have and save Israel out of Midian's hand. Am I not sending you?"
15 "But Lord,” Gideon asked, "how can I save Israel? My clan is the weakest in Manasseh, and I am the least in my family."
16 The Lord answered, "I will be with you, and you will strike down all the Midianites together."
17 Gideon replied, "If now I have found favor in your eyes, give me a sign that it is really you talking to me.
18 Please do not go away until I come back and bring my offering and set it before you."
And the Lord said, "I will wait until you return."
19 Gideon went in, prepared a young goat, and from an ephah of flour he made bread without yeast. Putting the meat in a basket and its broth in a pot, he brought them out and offered them to him under the oak.
20 The angel of God said to him, "Take the meat and the unleavened bread, place them on this rock, and pour out the broth." And Gideon did so.
21 With the tip of the staff that was in his hand, the angel of the Lord touched the meat and the unleavened bread. Fire flared from the rock, consuming the meat and the bread. And the angel of the Lord disappeared.
22 When Gideon realized that it was the angel of the Lord, he exclaimed, "Ah, Sovereign Lord! I have seen the angel of the Lord face to face!"
23 But the Lord said to him, "Peace! Do not be afraid. You are not going to die."
24 So Gideon built an altar to the Lord there and called it The Lord is Peace. To this day it stands in Ophrah of the Abiezrites.
25 That same night the Lord said to him, "Take the second bull from your father's herd, the one seven years old.Tear down your father's altar to Baal and cut down the Asherah pole beside it.
26 Then build a proper kind of altar to the Lord your God on the top of this height. Using the wood of the Asherah pole that you cut down, offer the second bull as a burnt offering."
27 So Gideon took ten of his servants and did as the Lord told him. But because he was afraid of his family and the men of the town, he did it at night rather than in the daytime.
28 In the morning when the men of the town got up, there was Baal's altar, demolished, with the Asherah pole beside it cut down and the second bull sacrificed on the newly built altar!
I rest my case !
hope this helps !!!