The third word of the Hebrew Bible is Elohim: “Bereshìt barà Elohim …” “At the beginning God created … “. So, at the very beginning of the Hebrew Bible we find a reference to polytheism? The verb barà (created) is singular, so the author was convinced that there was only one God. Why then did he write Elohim?
Elohim’s meaning is not only “God”, but also “angels, gods, divine beings” and we have occurrences of these terms throughout the Hebrew Bible. Gramatically, the singular of Elohim is El or Eloah but these words are usually not used in the Bible. Why the plural?
Because the plural is the sum of all meanings of Elohim and the proper name of Israelites God is NOT Elohim but Yahvè! (cf. Exodus chap. 3) Yahvè has assimilated all meanings of Elohim, and Elohim has assimilated the name Yahvè. Evidence of this is in the 2nd chapter of Genesis, where we always find “Yahvè Elohim” that means “the Lord God” or “The Lord of gods”, namely the Supreme God, the only God.
Writing the name of God, the Genesis author had in mind the Supreme God, the only God, the sum of all gods, angels and divine powers. Probably, he had in mind Yahvè while he was writing Elohim.