What does "understand it" mean? No one reading it today can "understand it" as someone then did. We simply do not have the same referents to work from so general consensus today will never match how it would have been perceived then. And furthermore, no two people looking at the same thing today will understand that thing in exactly the same way, just as no two people did back then either. But when you add the variable of distance of time and removal of cultural, that perception of the past will vary even more between two people today. Not even to bring in stages of growth into this, how a person of 15 interprets and "understands" things in his world in vastly different ways than someone of 50.
So, to those who believe the Bible is God's direct word, even if so, when it hits our eyes it will refract and spray out into a trillion different colors of meaning. Which one of those colors is the truth? And furthermore, and more to the point, can truth even be definable as a thing? So what is "understanding" then? How do you ascertain that?
So what I see as what is pertinent, is that someone today looking at the OT, from a Christian context, they are seeing God through the filters of what they perceive today. They find reflections of colors that register with the palate of colors that resonate with them. Literature like this, like sacred scriptures, should not be approached like a science or history book (even if it uses those a backdrops for its underlying story). They are not technical manuals. They speak Truth, through what we perceive in them through ourselves. They become vehicles to open us to an inner world of truth. To treat them as technical manuals, so to speak, squeezes the life out of them. It flattens them, and flattens spirit as well.
So in this sense, when looking a sacred texts they are inspired texts, as they are expression of the human spirit, speaking Truth in an fallible package. In this sense, they are the word of God, through the human spirit. To say they are textually and historically and scientifically infallible is to miss entirely what can be heard in them.