I don't know hat went through the minds of the people who wrote the Scriptures.  All that I know is that authors used those types of literary conventions at that time.  I look at Divine inspiration differently than you do.  I believe that the writers of Scripture passed on to us the very radical teachings of Jesus about the love o God and of neighbor.  Those teachings are radical even today.  
Re Ehrman -- he is not telling people what to believe.  He is teaching about how Scriptures were written, about the way that they were understood and received contemporaneously, about the beliefs of the people of the time, etc.  He is very respectful of belief and does not suggest in his writings that people ought to reject faith.