It is a pretty complex issue inasmuch as the OT text itself is, in a sense, the cradle of "God". The earlier/lower strata of the earliest stories are clearly grounded in polytheism, whereas the later/higher strata reflect a monotheistic edition (writing or rewriting). The result is a text that is monotheistic at face value but that often makes no sense without a polytheistic background.
In the older polytheistic context, Yhwh is definitely not a group of gods, but a god (a son of El, the Father of gods and men) among others. The best OT polytheistic synthesis is found (thanks to the diverging corrections of the Hebrew Masoretic text [MT] and the Greek Septuagint [LXX], with the confirmation of a Qumran manuscript) in Deuteronomy 32:8f:
When the Most High apportioned the nations,
when he divided humankind,
he fixed the boundaries of the peoples
according to the number of the gods (originally 'sons of El'; MT 'sons of Israel,' LXX 'angels of God')
Yhwh's own portion was his people,
Jacob his allotted share.
Here Yhwh is the patron god of Israel, equal to the other gods (siblings) in charge of other nations, as also appears in Judges 11:24:
Should you not possess what your god Chemosh gives you to possess? And should we not be the ones to possess everything that our god Yhwh has conquered for our benefit?
But as polytheism became henotheism Yhwh was increasingly identified with El, the head of the divine assembly -- he is the God of gods, the Lord of gods, the King of gods (Deuteronomy, Psalms). At a later stage he becomes the monotheistic "God" -- there is no other god. At this later stage he is not only one of the 'elohim (real plural), a 'elohim (real singular in spite of the plural form, equally found for other gods) -- but THE 'elohim which may be analysed as combining the plural and singular senses: "God" uniting, as it were, the former "gods" into himself.
Normally in Hebrew the singular and plural 'elohim are distinguished by the number agreement of verbs and adjectives (that is, when there is a verb or an adjective). And the monotheistic redaction has left the polytheistic plural in many places, especially when the expression was supposed to reflect a non-Israelite opinion. This is the case in 1 Samuel 4:8 (the Philistines):
Who can deliver us from the power of these (plural) mighty (plural) gods ('elohim)? These (plural) are the gods ('elohim) who struck (plural) the Egyptians with every sort of plague in the wilderness.
This is also the case when a supposed "monotheist" is viewed as adapting to polytheistic speech, e.g. Jacob in Genesis 20:13:
And when God / the gods caused me to wander (plural) from my father's house...
Or perhaps Jacob was regarded as a polytheist, since the same thing happens in Genesis 35:7 in the narrator's speech:
it was there that God / the gods had revealed himself / themselves (plural) to him when he fled from his brother.
Plural is also found when Israelite "apostates" are speaking, e.g. Exodus 32:1ff:
the people gathered around Aaron, and said to him, "Come, make gods for us, who shall go (plural) before us...
Many other cases are ambiguous for a lack of verb or adjective in either number, e.g. Genesis 3:5 ("knowing" is in the plural, but can refer either to the "gods" or to "you"); 21:22,33; 40:8; 41:16,38; 42:18...
In short, I think the equivalence "Yhwh = the gods" may reflect, not the original identity of Yhwh, but his later monotheistic status as explained in a wider polytheistic context (Yhwh = God = the total sum of the divine realm which the polytheists "misconstrue" as "gods").
