that it developed out of the conversation at the burning bush. I don't have a Bible handy, but paraphrased it went something like this:
God: "Go tell Pharoh to let my people go."
Moses: "But don't even know you! Who should I say sent me? What is your name."
God: "I am who I am."
So, Moses went to Pharoh and when Pharoh asked who his God was, Moses replied "He is I am."
I guess I don't truly understand all the other stuff you were talking about, since you seem to just rule out the "he is I am" construct. I don't know much about words and language development, so I guess I'm at a loss. The thing that I would point to is Eyeless Myrdraal's post, and also another example from the New Testament:
(I don't have the reference, but I'll try to get it as soon as I can) Jesus was talking to the Jews, giving a lecture. At first they are all amazed at what he is saying, but then he says this line: "I tell you the truth, before there was time, I am!" The Jews get so mad at this that they proceed to pick up rocks to stone him, but Jesus escapes.
The reason they get so mad (according to two different commentaries) is that when Jesus said "I am" he was invoking the name of God - not only that, but also applying it to himself. Now, I don't know what that is in the original Greek, but it would be interesting to compare. Also, it doesn't seem to me that if Jesus said "I tell you the truth, before there was time, I cause to fall (or I blow)" that it wouldn't have quite the same effect.
Like I said, I don't really know any etimology, so I can't disagree with you on that level. It just seems to me that Occam's Razor ought to be applied (*Occam's Razor: the simplest explanation is most likely the correct one).
Let me know what you think...
:: I am the speaker at the dawn of the age
:: and I stand at the door to the west.
~X~