I think that most of the Bible, or at least the Old Testament with which I'm more familiar, is a mixture of fables meant to teach lessons and historical reporting, much of which was distorted and embellished as it was passed down orally before it was finally written. My take on whether the Bible was written by God is that belief in God inspired man to write it. Any work of art, poetry, or inspired creation can be said to be created by God with man as His instrument. This, of course, can never be proven or disproven because it is a matter of faith.
I see the analogy between the ark and Christ, but I think it's a strtetch . . . or maybe two unrelated stories, both of which are expressions of man's hope for divine salvation.