At this point in the Word, the style is story telling. At Genesis 12, the Word switches styles to historical fact where the internal sense there is the prophecy of Jesus Christ's nativity.
Good point. Prior to Gen. 12, the bible is pre-history. Unlike the rest of the bible, the first 11 chapters of Genesis are, on their face, not recording any memory of events. To assert that they were a literal chronology of historic events would be to assert direct revelation, which did not happen until Christ. Rather, they are true myth.
The word "myth" has been destroyed by modernists. It is now believed that "myth" means a falsely held common notion. Dictionary.com's first definition is problemmatic, but suffices: "A traditional, typically ancient story dealing with supernatural beings, ancestors, or heroes that serves as a fundamental type in the worldview of a people, as by explaining aspects of the natural world or delineating the psychology, customs, or ideals of society: the myth of Eros and Psyche; a creation myth."
What distinguishes the Creation myth from pagan myths is not that it is historical, while pagan myths are not. It is that the Creation myth is wholly true, while pagan myths are not.
The fall of Adam describes our own fall, and the essence of our broken relationship with God. It is myth, but it is true myth.