I read the Old Testament differently from many of my coreligionists. I don't read it as an historical narrative at all. As far as I'm concerned, it doesn't matter whether any of the events described in the OT happened. In fact, I would be disappointed to learn that God ever sanctioned genocide or that some of the other disturbing events took place.
The Creation Story is simply a myth, and there is no reason to believe that creation happened as described. That doesn't make the story worthless, though. It just means it has to be understood differently and that you have to work to glean the wisdom from it. The same goes for the Tower of Babel and the Deluge. These things never happened. The stories are valuable, however, in that they reveal how the understanding of God emerged and developed over the centuries among the Jews. The reason that God seems so different in the early books and the later books is that the understanding of God matured over time. At first, God is just like every other deity. You have to placate him with barbecue or He'll smite you. He might smite you anyway. Only later is God concerned with justice and mercy.
Exodus probably didn't happen the way it is described in the Bible, either. I reckon some of the Jews who made up the tribes of Israel had come out of Egypt, and their story, with embellishments, was mythologically useful and served to legitimize the takeover of Palestine and support the national identity. There's good stuff in there; don't get me wrong. But you have to read it for what it really is and to understand it as myth, not as a history book.
The lists of rules and laws is interesting, but there's really no reason to believe that God transmitted this minutiae to the Jewish priests. That was just the customary law that developed among the Jews, and it should be taken for what it's worth. There's no good reason to believe that these laws and rules are appropriate for any society today. You can follow them if you want, but you should really have a better reason for doing so than that they were written down a long time ago and that the authors claimed that they came from God. If I told you that this blog post came from God, would you believe that?
The prophets were writing about their own times and circumstances, so there's no use looking for predictions about now or the near future. That doesn't mean the prophets aren't valuable. They're just valuable in other ways.
Psalms are fabulous poems and should be read as the poet's devotions. The proverbs are just a bunch of sayings that are or or less wise. Some suggest that the righteous always prosper and that the wicked get their comeuppance, but we all know that's just not true. The concept of God in such writings was unsophisticated: if you follow all these rules, only good will come to you. Ecclesiastes is better.
Some would argue that my way of looking at the OT makes for too much freedom of interpretation and diminishes the authority of Scripture. I'll grant the latter, but I don't think you can have too much freedom. I trust the Holy Ghost to guide the reader.