Peterson's speaking of Western, Judeo-Christian culture, not universal human experience.
"Roughly speaking. we [Western culture]have a bedrock of agreement -- that's The Bible, by the way."
"Literally there was only one book, like, as far as our Western culture's concerned..."
The Bible's a compilation of ancient writings and legends. The writings included have changed over time. The standard Catholic and Protestant books were not decreed by God, they were voted on by a specific sect, at specific conferences, to support a specific narrative. Some gospels and writings were included, some rejected. Since then, it's been heavily revised and edited, by men, with agendas.
Our "foundational book" is an accident of history, "because of the arbitrary dictates of power."