Hi, Leolaia.
I respect your learning.
And I appreciate your close investigation.
But I feel that I may have to say to you.
First, you should explain exactly to people that that text which you have quoted from LXX is "translation into English from Greek."
And if people compare in the Greek original, people will understand that the Apostle Paul is not quoted strictly each time.
When he quoted from LXX in many cases, he quoted having put the words in another way, or translating freely (paraphrase).
Therefore, the word of the Old Testament and the word of the New Testament are not necessarily strictly in agreement as you showed.
He quoted the Scriptures freely and applied freely.
Moreover, according to my understanding, the Apostle Paul understood that Jesus is "I AM."
Therefore, it is natural that he applies the words about "I AM" (Jehovah) of the Old Testament to Jesus.
But it can be strictly said so in a "symbolic meaning."
If you thought literally "Jehovah is Jesus", when Jesus comes to the earth, it means "There is no God in Heaven."
I think that it is an absurd view.
Jehovah's Witnesses will surely make a fool of such views.
And they will make a fool of people who gather to JWD.
possible
http://bb2.atbb.jp/possible/