Their are multiple ancient versions though, most with minor differences but apparently there are a couple with major divergences according to translators although they hadn't published the full texts last I heard.
This is the written version that has the flood story.
It's the authoritative version. This is the one in the school books.
The flood story excited the archeologists who dug up the clay tablets in the ruins of the Assyrian King Asherbanipal's library.
The story survived three cultures--Sumerian, Babylonians and Assyrian. (Susan B. Anthony).
The Sumerians had Gilgamesh stories but the Babylonians put them into a unified epic.