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.
We believe that Adam and Noah represent Churches.
I used to say 'think of the creation story like a parable' but I'm changing the meaning of language to avoid using a perfectly good word:
"Webster's Revised Unabridged Dictionary (1913)" Myth Myth, n. Written also mythe. Gr. my^qos myth, fable, tale, talk, speech: cf. F. mythe.
1. A story of great but unknown age which originally embodied a belief regarding some fact or phenomenon of experience, and in which often the forces of nature and of the soul are personified; an ancient legend of a god, a hero, the origin of a race, etc.; a wonder story of prehistoric origin; a popular fable which is, or has been, received as historical.