It is, indeed, mythology. And therein lies the rub.
The theology is in the Mishnah. The oral tradition of religious catechesis that now makes up the Mishnah came first.
Evenfually, the mishnaic traditions became "storyized," turned into narrative for liturgical purposes. This dramatization of our religion is the Bible.
Later, the mishnaic traditions got written down in the book form of the Mishnah itself. That is the theology and doctrine.
This later became codified into the Talmud because in Judaism adherence to the Mosaic Law as written is wrong. The written form in Scripture is a static snapshot, and it actually violates the Law if you apply it today as how it was understood in the past. Mishnah teaches that Torah is a living breathing thing, adjusting with the times to make "tikklun olam" or service to our neighbors possible. You cannot serve your neighbor in the here and now by forcing them to be as it was long ago.
The Bible is like the Cecil B. DeMille film "The Ten Commandments." It is a dramatization of the real thing found in Mishnah. The Bible is the dramatized, mythology version, with liberties taken for teaching purposes.
So the idea that calling the Bible a bunch of myths just makes a Jew say: "Now you're talking like a Jew!" These myths contain our religious truths, but merely the substance transferred from our religion. The Jehovah's Witnesses, on the other hand, told you that the Cecil B. DeMille version is the historically accurate version with doctrine included, and that's just not true.
By what you said, you validate Judaism. You are finally getting it.