That’s far from fact. Certainly, when reading the Bible as it ended up, that is what the editors intended. But the historical record does not support that.
True, and the reason for all of the different names is because many of the things in the OT were plagiarized from earlier sources. A reference to El might literally be a reference to El, because the text was lifted from an ancient poem about El. Alternately, the word “Hadad” may have been scribbled out and replaced with “Yahweh”, or so on and so forth.
Quartz Hill School of Theology (Not necessarily the best source, but relatively concise)
Many of the best poems were ones which had no explicit mention of a particular god’s name. If it just said, “His Greatness”, “The Lord”, “The Master”, etc. then that makes it much easier to incorporate. And likely, to be fair, text that was written about Yahweh, by different people, who had their own way of referring to Him was incorporated as well.
To be even more fair, it is likely that by the 6th Century BC, Yahweh had completely usurped the position of El in the pantheon. In Ugaritic poetry, Ba’al was taking over the pantheon from El. In Greece, just to the North, Zeus seems to have overtaken Cronus in the pantheon and the Greeks, on hearing about the history of the Hebrews, came to the conclusion that the god they called El was the one they called Cronus. To the East, Ashur overtook Enlil. To the West (though quite a bit earlier), the god Amun was raised up and synchronized with Ra.
If you delve deeper into history, you’ll find that when people talk about a particular pantheon of deities was, they’re really just referring to a particular, popular snapshot of time that (probably) is well-attested to by documentation. But the reality is that pantheons are fluid. Ashur, for example, started out as the deification of a city and eventually ended up as the creator of the world.
But, if one is willing to accept that, then you must accept that who a deity is varies based on fashion and political expedience. When Greece rose in prominence, in the world, the Roman pantheon came to look a lot like Greece’s. When the Persians rose to prominence, the Jewish religion came to look a lot like the Persian.
There’s almost no information about who Yahweh was, before the Bible. It seems reasonably conclusive that he had a female half. Beyond that, there is not much that can be said. And though we can show references to El and Baal at the Kuntillet Ajrut, it is always possible that the place was built for travelers from different places, with different gods. King Solomon established places of worship for Baal, but supposedly just for his wife. Ultimately, there’s no way to know what the intention was of a particular structure that we find, minus some good written text. But we can be relatively certain that the OT wasn’t above baldfaced lies, nor can we trust that the writers weren’t complete charlatans.
To say that Yahweh was ever subservient to El is currently not something that can be conclusively stated. Potentially, Yahweh was never part of any pantheon that included El and, as used in the Bible, “El” is just a word meaning “God”. But, that El was a separate, unrelated god at one time is completely certain. Based on the history of the Jewish people, as related by the OT, the Hebrews certainly seem to trace their roots back to a people who worshiped El in the same fashion as the Canaanites.
There is tantalizing evidence that “Yahweh” was one of the sons of God, but the evidence is not strong. It’s also plausible that Yam is the ancient name for Yahweh, as evinced through the name of Abiyam, the great grandson of King David. Though, the poetry which is associated with Yahweh, in the Bible, generally utilizes images of weather control, thunder, and living on a mountain. These are closer to Hadad/Moloch/Chemosh than to Yam (the god of the Sea), so the link would be rather strange. (Though, if a city can become to creator of the world, having a god of the sea become a warrior god is far from impossible.)