If what you say is true, then Jehovah would be a false god. The facts prove he is the true God, IMO. For example, Jehovah had numerous prophecies recorded in the Bible, all of which came true or will come true. One example is his naming Cyrus as Babylon's conqueror, some 200 years before these events occurred., perhaps 150 years before Cyrus was born. There are many other examples. (Isaiah 44:26-28)
As to the Bible's creation account coming from a mythic god, this claim is often made and never substantiated. Comparing the Genesis account to pagan myths is like comparing a mansion to a tent.
Zoroastrianism was, Historically verifiable, a prominent religion in Persia during what you would call the Babylonian Exile... Just go read their origin accounts. Read up on their philosophies of good and evil - on the nature of god - on everything.
Jehova is a false god, just like Ahura Mazda is a false god.
It's always interesting, when reading old books that aren't properly dated, how we assume that a prophecy isn't actually just a piece of history that was recorded as a prophecy.
I like your analogy at the end, you just have it backwards historically. You're assuming that the one you have chosen supersedes the others, but you're mistaken. Christianity, and even Judaism, are evolved version of religions that came before it. As the Hebrews traveled through whatever regions they were in, they adapted their own belief system based on snippets of those that surrounded them.
The code of Hammurabi
The Epic of Gilgamesh
The mentioned creation by Ahura Mazda
Etc, etc...
Throw in some other smaller myths that you come across while traveling, adapt them to your own people, places, names, and cities, and you suddenly have an oral history (some written) which starts a new religion.
I'm sure you believe that Islam is adapted from Jewish and Christian stories, inserting differing views on certain events in order to give itself prominence. Judaism is the same thing, but using ancient religions that no one really pays any attention to anymore. Add a little bit of Saul of Tarsus, with a dash of historical reference to the Romans, and baby you've got yourself a stew going.
Just because Christianity is the religion that you have chosen to follow doesn't make it any more susceptible to these common historical practices in the evolution of religion.
Just look up the stuff I've mentioned. You seem like a rational person. You'll see what I'm talking about. Biblical Archaeology was my minor. It's what I know.