The Hypothesis #1 “God is speaking to members of his heavenly council” (aka Angels) is also my opinion on this, since there’s apparently no mention of the use of the majestic plural in Ancient Hebrew.
Also, agreed with Explanation #5 “comes from commentators who hold to minimalist, deconstructionist, evolutionary views of biblical religion. They do not take seriously the rigorous anti-pagan, anti-mythological theology in Genesis and the rest of the Bible. Their approach is actually unhistorical, for they impose personal skeptical unbeliefs on the Text while ignoring the Text’s internal witness”. This is further supported by the anti-myth nature of the text. Also, although it is true that the israeliste folks worshipped other gods, this worship was mostly limited to domestic idolatry, so it’s very unlikely that the people who wrote the sacred texts (the israelite elite: priests, prophets, etc.) would write it that way.
And finally, for explanation #6, the ancient Hebrew writers didn’t know about the trinity, although this seems to be an interesting point: "In later history, Israel’s prophets envisioned a “Lord” (Adon) who sat beside God as vice-regent; an image enacted materially by the Davidic kings who sat on God’s throne in Jerusalem.
This imagery of God-and-his-Lord comes from two primary Hebrew texts: Psalm 110:1 and Daniel 7:9-14. And both passages are central to Yeshua’s self-identification as God’s Lord, and to the apostles’ apologetic about Yeshua (Matt 22:41-46; 26:63-65; John 17:3; Acts 7:55-56; Eph 1:20-23; 1 Tim 5:21; 6:13; Heb 1:2-3)."