Some folks, in their quest for literalness fail to see the underlying message. Take the Flood story you've brought up. We all know that there is no evidence for a universal flood -- especially one of the monumental proportions spoken of in the Bible. However, the story can be read as an allegory. Noah was "saved" because he had faith in the Almighty. The story lets the reader know that, no matter what happens, including having your whole world (figuratively) washed away, in the end you will be fine as long as you trust God. One can see this as an allegory alluding to the message presented in the New Testament.
However, as I said before, the beauty of this message will be completely lost on some people because their eyes see only the forest (the literal words of Scripture) and not the trees (the meaning of those Scriptures).