Interesting topic and a complex one. But my take from a Biblicalist point of view is that since everyone is descendant from Noah, that it is reasonable that they understood or adapted concepts of the Creator and indeed would have been potential worshipers, or just acknowledge him in the pantheon of these other "gods" who probably can be linked to the principle angels involved.
Case in point the ancient Sumerians concept of VIRGO, a virgin carrying a branch, representing the "virgin mother" is a clear concept of Satan as portrayed in Eden as "the woman and her seed." The branch represents her family tree or her seed. Thus women holding a seed (like Athena) or Virgo, all Mother Goddesses are directly based upon Satan's idenity in Eden as the woman.
So if that concept was so clear and fresh in Sumer and they understood who Virgo was and what happened, then I think it's quite possible for them to have had a concept of El and may have paid some perfuntory worship to him.
Another issue we have to deal with in regard to early worship of YHWH who may have very well been called El just as we say, "God" and everybody knows what/who we're talking about, is MELCHIZEDEK. He was a Canaanite, living at Jerusalem, which apparently was a center of worship of YHWH since he was a king-priest of Yahweh. So is Melchizedek from the time of Abraham was already set up as priest of El/YHWH then we have direct Biblical proof that some of the Canaanites indeed worshipped El and understood who he was.
Finally, the destruction the Jews did in Canaan was a timed event. Canaan had a certain period of time to remain in charge of their land before the Israelites took over. So it's possible that Canaan had been a center of YHWH worship early on and had become totally corrupted and rebelled and so their destruction was connected with this rebellion against YHWH. And other accounts clearly show the Canaanites knew who EL/YHWH was, even if that concept had become corrupted over time.
Or take Greek mythology as another example. Those concepts of the one great father-god figure and the angels coming down and marrying beautiful women, many attribute to the angels marrying women before the flood, etc.
Having noted that, the only true issue here is not whether or not the Canaanites influenced the Jews and their concept of El and YHWH many, many years later, but that the original concepts of the creator, the angels that rebelled, even Satan as handed down by Noah had their own parallel but independent developments.
Sorry for this astrophic. I wanted to just show the ancient Sumerian concept of VIRGO, a woman holding a branch, representing the "woman and her seed" who represents the Mother Goddess, who is Satan/Lillith is ancient mythology. If they knew precisely who Satan was, I would think they would know just as precisely who El was. At least some of them.
Here is another form of the "woman and her seed", Satan as the Mother Goddess in the form of Ceres from Pompei. Notice the sheaf of grain.
Another of Ceres holding a sheaf.
Satan depicted as a woman frquently and consistently in religious art:
http://ccat.sas.upenn.edu/humm/Topics/Lilith/aNePics.html
So the Canaanites knew generally or precisely (i.e. Melchizedek) who the creator-god was and had specific concepts of Satan/the Mother Goddess as well. So the Canaanites calling the Creator "El" is not inconsistent with Biblical history, but doesn't mean that Abraham or the Jews needed the Canaanites to develop their concept of YHWH, which would have been handed down to them via Noah as much as he handed those concepts and events in Eden down to everybody.
That's why early on the idea of needing to connect Canaanite religion to YHWH worship fails immediately for "The Bible Unearthed." There's no need for any connection other than the common source through Noah. Further, nobody is saying that there wasn't some YHWH worship going on in Canaan under the name of "El", as long as El had the concept of the great creator-father god figure, which apparently he did. Thus I find Finkelstein's aggressive presumptions about the basis of Jewish worship of YHWH with reference to a foundation in Canaan a bit short-sighted, IMHO. But he's certainly entitled to attempt to make the connection.
JCanon