The Bible intermingles mystery, confusion, revelation, and inspiration in a single narrative about real life because real life involves all of these contradictory elements. To be real and true, the story of humanity has to be contradictory because we as humans are inconsistent and contradictory in our search for truth and meaning. Nothing defines humanity so much as confused mental states and dramatic swings in mood and awareness. Our minds and emotions are as fickle as the Bible’s depiction of God make Him appear.
The Bible is concurrently the story of God and the story of humanity because God and his creation exist as a unity. To tell of one is to tell of the other.