Guess what? God didn't write the Bible. Some bearded Jews did. But you can believe what you like.
I wouldn't take their word, especially after some much time has passed and we know much more about the world.
Another thing, let's assume God really spoke through the Bible. How would he explain evolution to some warring desert tribes? It would be easier for them to just think that "God created everything". For the same reason we don't teach evolutionary biology in kindergarten. Even adults have trouble understanding it