It's funny how, above, I summed up screenfuls of Leolaia posts very succinctly, and yet my own post still ended up as a screenful of text because I summed up so much information of hers.
Here's a summary of my summary: the worship of YHWH was apparently introduced well after the people in Canaan/Israel were worshiping El. It may have come from the Midianites or from the Kenites (or both). (The "Shasu of Yhw" of Egyptian record may have been one of these southern nomadic tribes.) They were then integrated into Israel as a tribe of priests. These priests were the ones who read and wrote the records, therefore they got to determine what Israel's history was. Naturally they inserted their own traditions into the existing traditions of patriarchs like Yakov (Jacob), adding a side-story where the Israelites spent time in Egypt and were delivered by God from slavery.
So the traditions of this southern nomad tribe (or perhaps even actual escaped, Egyptian slaves, or former Egyptian wa'ebs, or maybe exiled worshippers of Aten -- the last idea not being promoted by Leolaia, mind you) became part of the identity of the Jews, even though the Semitic people that most of the Jews were descended from probably hadn't ever gone anywhere near Egypt.
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As I stated earlier, it could be that the nomads who worshipped YHWH were in awe of a volcano they had witnessed. Alternately, they simply believed that mountains (non-volcanic ones, even) were holy because they were closer to the sky. But they had to find a way to reconcile worship of their one true God YHWH with the local peoples' polytheism or henotheism, since they worshipped Baal, El, Asherah, etc. So the priests gradually shifted El's qualities and status as Creator over to YHWH (such as by saying in Ex. 6:2, 3, and implying in Ex. 3:15, that the patriarchs worshipped YHWH as "El Shaddai" without knowing his real name), then they also kicked the wife Asherah out of the picture. Can anyone say "new light"?
The continual discovery of small idols (household gods, little Asherahs and such) testifies to the fact that the monotheism of the Bible was an ideal which the priests were constantly trying to force on the people (such as by telling stories where the patriarchs give up their bad old habits by burying their teraphim), with limited success. Much of the rule-making and redactions of older beliefs in the books of the OT may be little more than wishful thinking by control freaks, while the common peoples rolled their eyes at the priests behind their back. Sound familiar?
P.S.: Interesting footnote: Jon Preston quotes a WT that says Baal-Hadad was called "rider of the clouds". The same process that I described above, of "converting" El into YHWH, was done with Baal->YHWH. YHWH is the "rider of the clouds" in numerous verses which Leolaia lists here: http://www.jehovahs-witness.net/jw/friends/65165/1/The-Rainbow-and-the-Flood.