Agreed, Jesus isn't YHWH. However, He is YHWH's agent. As such He speaks on YHWH's behalf and often in the 1st person. The Apostle John said no one has seen God at any time, the only begotten Son has made Him known. So no one had ever seen YHWH. That means that in all of those OT passages where someone encountered YHWH, it was the Son. Paul said no one Has seen nor can see God. So YHWH can't even be seen. He's the invisible God. That begs the Question, if no one has seen nor can see YHWH, who was it that they saw. It was YHWH's agent. YHWH' name is on Him.
Behold,
I send an Angel before thee, to keep thee in the way, and to bring thee into the place which I have prepared. Beware of him, and obey his voice,
provoke him not; for he will not pardon your transgressions: for my name is in him. But if thou shalt indeed obey his voice, and do all that I speak; then I will be an enemy unto thine enemies, and an adversary unto thine adversaries. For mine Angel shall go before thee, and bring thee in unto the Amorites, and the Hittites, and the Perizzites, and the Canaanites, and the Hivites, and the Jebusites: and I will cut them off.
The Holy Bible: King James Version. 2009. Electronic Edition of the 1900 Authorized Version. Bellingham, WA: Logos Research Systems, Inc.
Notice YHWH sends His Angel or Messenger. YHWH says, "My name is in Him." The Septuagint says, "my name is on Him."
We actually see this I Genesis 19.
Then the
Lord rained upon Sodom and upon Gomorrah brimstone and fire from the
Lord out of heaven; And he overthrew those cities, and all the plain, and all the inhabitants of the cities, and that which grew upon the ground.
The Holy Bible: King James Version. 2009. Electronic Edition of the 1900 Authorized Version. Bellingham, WA: Logos Research Systems, Inc.
In this passage both occurances of the word LORD are YHWH. So, we have two who are called YHWH. One is on Earth and He calls down fire and brimstone from the One in Heaven.
It seems obvious that if there is only one YHWH, but we have two here, one of them must be acting on behalf of the other and using His name in the first person. We know the YHWH on earth was previously dining with Abraham so He couldn't be the invisible YHWH. Thus He must be YHWH's agent. John said no one has seen God at any time, the only begotten Son has made Him known. Thus, this one called YHWH who dined Abraham must be the Only Begotten Son.