odds are they were out and out polytheists, and through revelation to Moses they became montheistic.
for evidence related to this see,
Did God have a wife?: archaeology and folk religion in ancient Israel By William G. Dever
Break down their altars, smash their sacred stones and cut down their Asherah poles.
This is what you are to do to them: Break down their altars, smash their sacred stones, cut down their Asherah poles and burn their idols in the fire.
Break down their altars, smash their sacred stones and burn their Asherah poles in the fire; cut down the idols of their gods and wipe out their names from those places.
Worshiping Other Gods ] Do not set up any wooden Asherah pole beside the altar you build to the LORD your God,
Othniel ] The Israelites did evil in the eyes of the LORD; they forgot the LORD their God and served the Baals and the Asherahs.
There is evidence of literary borrowing concerning whom God is too,
Religious Context. The religion of Ugarit and the religion of ancient Israel were not the same, but there were some striking overlaps. For example, the name of the ultimate divine authority at Ugarit was El, one of the names of the God of Israel (e.g., Gen 33:20). El was described as an aged god with white hair, seated on a throne. However, at Ugarit, El was sovereign, but another god ran things on earth for El as his vizier. That god’s name was Baal, a name quite familiar to anyone who has read the Old Testament. At Ugarit Baal was known by several titles: “king of the gods,” “the Most High,” “Prince Baal” (baal zbl), and—most importantly for our discussion—“the Rider on the Clouds.”
Baal’s position as “king of the gods” in Ugarit, Israel’s northern neighbor, helps explain the “Baal problem” in the Old Testament. ...
“The Cloud Rider”
Throughout the Ugaritic texts, Baal is repeatedly called “the one who rides the clouds,” or “the one who mounts the clouds.” The description is recognized as an official title of Baal. No angel or lesser being bore the title. As such, everyone in Israel who heard this title associated it with a deity, not a man or an angel.
Part of the literary strategy of the Israelite prophets was to take this well-known title and attribute it to Yahweh in some way. Consequently, Yahweh, the God of Israel, bears this descriptive title in several places in the Old Testament (Isaiah 19:1; Deuteronomy 33:26; Psalm 68:33; 104:3). For a faithful Israelite, then, there was only one god who “rode” on the clouds: Yahweh.
Until we hit Daniel 7, that is. You know the scene, but you likely don’t know the full context, since Ugaritic provides that for us:
9 As I looked on, the thrones were set in place, and the Ancient of Days took His seat. His garment was like white snow, and the hair of His head was like lamb's wool. His throne was fiery flames; its wheels were blazing fire. 10 A river of fire streamed forth before Him; thousands upon thousands served Him; myriads upon myriads attended Him; the court sat and the books were opened . . . 13 As I looked on, in the night vision, One like a son of man came with the clouds of heaven; he came to the Ancient of Days and was presented to Him. 14 Dominion, glory, and kingship were given to him; all peoples and nations of every language must serve him. His dominion is an everlasting dominion that shall not pass away, and his kingship, one that shall not be destroyed.
The plurality of thrones in the passage tell us plainly that we have here what scholars of the Hebrew Bible call a divine council scene — the high sovereign in his throne room, meeting with the heavenly host. The literature of Ugarit has many such scenes, and the biblical divine council and the council at Ugarit are very similar. In point of fact, the flow of Daniel 7 actually follows the flow of a divine council scene in the Baal Cycle:
Ugarit / Baal Cycle Daniel 7
(A) El, the aged high God, is the ultimate sovereign in the council. (A) The Ancient of Days, the God of Israel is seated on the fiery, wheeled throne (cf. Ezekiel 1). Like Ugaritic El, he is white haired and aged (“ancient”).
(B) El bestows kingship upon the god Baal, the Cloud-Rider, after Baal defeats the god Yamm in battle. (B) Yahweh-El, the Ancient of Days, bestows kingship upon the Son of Man who rides the clouds after the beast from the sea (yamma) is destroyed.
(C) Baal is king of the gods and El's vizier. His rule is everlasting. (C) The Son of Man is given everlasting dominion over the nations. He rules at the right hand of God.
The striking parallels are especially noteworthy given that this is the only time in the Old Testament where a second personage other than Yahweh is described as “coming with/upon the clouds” (the preposition in Aramaic can be translated either way). The intent of the author to describe this “son of man” with a title reserved only for Yahweh was clear by virtue of how the scene followed the Baal literature — the literary cycle whose central character, Baal, held the Cloud-Rider title!