By the end of the biblical period, monotheism had won.
Monotheism had won so much that on the whole we have forgotten what pagan religion was about. Most people could not tell you what the word "pagan" means.
Monotheism had won so much so that even educated people think that pagan religion involved idol worship.
Monotheism had won so much so that college Departments of Religion today usually do not offer a course on pagan religion.
Richard Friedman, "The Exodus," page 193
When our father Abraham was born, a star rose in the east and swallowed four stars in the four corners of heaven. Nimrod's wizards said to him: To Terah, at this hour, a son has been born, out of whom will issue a people destined to inherit this world and the world-to-come. With your permission, let his father be given a house full of silver and gold, on condition that his newly born son be slain.
Nimrod sent word to Terah, saying: "Last night a son was born to you. Now give him to me, that we may slay him, and I will fill your house with silver and gold."
Terah said: "I reply with a parable that will make you understand my anguish. A horse was told, "Let us cut off your head, and we will give you a barnful of barley." The horse replied, "You fools! If you cut off my head, who will eat the barley?" So, too, if you slay my son, who will make use of the silver and gold?"
King Nimrod said: "From what you say, I gather that a son has indeed been born to you."
Terah: "A son was born, but he died."
Nimrod: "My offer was for a live son, not a dead one."
What did Terah do then? He hid him in a cave for three years, and the Holy One provided for the child two apertures - out of one issued oil, out of the other fine flour.
When Abraham was three years old, he went out of the cave and [observing the world] wondered in his heart: "Who created heaven and earth and me?"
All that day he prayed to the sun. In the evening, the sun set in the west and the moon rose in the east. Upon seeing the moon and the stars around it, he said: "This one must have created heaven and earth and me - these stars must be the moon's princes and courtiers."
So all night long he stood in prayer to the moon. In the morning, the moon sank in the west and son rose in the east. Then he said: "There is no might in either of these. There must be a higher Lord over them - to Him will I pray, and before Him will I prostrate myself."
Bet HaMidrash 2:118-196, Taken from The Book of Legends: Sefer Ha-aggadah, Haim Nahman Bialik and Yehoshua Ravnitzky, page 31.
(ח) בְּהַנְחֵ֤ל עֶלְיוֹן֙ גּוֹיִ֔ם בְּהַפְרִיד֖וֹ בְּנֵ֣י אָדָ֑ם יַצֵּב֙ גְּבֻלֹ֣ת עַמִּ֔ים לְמִסְפַּ֖ר בְּנֵ֥י יִשְׂרָאֵֽל׃
(8) When the Most High gave nations their homes And set the divisions of man, He fixed the boundaries of peoples In relation to the sons of Israel.*
(The Dead Sea Scrolls and the Septuagint substitute, B'nei Elohim, sons of Gods."
So the passage in the Song of Moses would mean that when God created the nations, He set them according to the number of the gods. That is, He made Greece and gave it to Zeus, He made Babylon and gave it to Marduk, He made Assyria and gave it to Ashur, and so on. Each people had its god.
Richard Friedman, "The Exodus" Page 171
(1) A psalm of Asaph. God stands in the divine assembly; among the divine beings* He pronounces judgment. (2) How long will you judge perversely, showing favor to the wicked?Selah. (3) Judge the wretched and the orphan, vindicate the lowly and the poor, (4) rescue the wretched and the needy; save them from the hand of the wicked. (5) They neither know nor understand, they go about in darkness; all the foundations of the earth totter. (6) I had taken you for divine beings, sons of the Most High, all of you; (7) but you shall die as men do, fall like any prince. (8) Arise, O God, judge the earth, for all the nations are Your possession.
*Friedman translates "divine beings" as "Gods"
(1) When human kind began to increase on earth and daughters were born to them, (2) the sons of God saw how beautiful the daughters of men were and took wives from among those that pleased them.— (3) The LORD said, “My breath shall not abide in man forever, since he too is flesh; let the days allowed him be one hundred and twenty years.”— (4) It was then, and later too, that the Nephilim appeared on earth—when the divine beings cohabited with the daughters of men, who bore them offspring. They were the heroes of old, the men of renown.
(22) And the LORD God said, “Now that the man has become like one of us, knowing good and bad, what if he should stretch out his hand and take also from the tree of life and eat, and live forever!”
"God speaks in the plural in these three primordial stories because there are still others to whom to speak... But sometime after the event at the Tower of Babylon these others start to die off. The disappearance of the divine plural occurs right there, 100 percent consistent with the demise of the gods." (Friedman, The Exodus, pages 180-181)
"In Ugarit itself, to restrict ourselves to some example from the ancient Near East, the Ba'al cycle of texts depicts the death, the violent death, of three of its divine principals: Yamm/Nahar; then his killer, Ba'al; who, in turn, is masticated by his killer, Mot; who himself is later dismembered. The Mesopotamian mythic text of Enuma Elish, likewise, treats the death and, at points, dismemberment of the deities Apsu, Tiamat, and Qingu. And in Mesopotamia as well, dead gods can be referred to as a category."
("How Gods Die, Biblically and Otherwise," Machinisit and Smith, quoted by Friedman on p. 181, The Exodus)