This poses many possible conclusions, even as a believer...
1) If God did not inspire every verse, how does one select which verses were inspired, and which ones were not?
2) If one concludes all verses are God inspired, and yet many humans disagree with slavery, this means many do not inherently agree with God's moral character; and are to instead follow commands.
3) I say the Bible was all written by men, with a limited understanding to all conclusions, at the time in which it was written.
I think the honest answer would be ... we don't know, and I don't know how any given individual can know that.
The claim that God inspired Bible is a subjective claim, obviously, because we have a long history of human disagreement on what would be "inspired" and what is uninspired.
Marin Luther, for example, ripped out some books from his Bible. Thomas Jefferson took the scissors and cut quite a bit.
I don't think that any individual subjective opinion, or even a consensus of opinion can resolve this issue, but it's a bit besides the point, because you seem to think that Christianity is a static concept outlined as words hammered in stone in some ancient book. That's not what it is. That would be something I call Biblianity, or Biblialotry... a worship of Bible as a "special magical book" that will tell you everything what's right and wrong about life.
That's not what it is likely is, at least not from what or how I understand it.
So, the above is your analytic approach to what it is, and it's typical to any reductionist thought. How can Bible be right, when it's wrong?
Well, the minister/chaplain in the scene above...
"River you don't fix the Bible... you let it fix you". And the context of that in the show is the River herself is pretty screwed up. She doesn't understand what reality is. She was a mind-controlled slave turned into a weapon. But, the girl's a genius.
Thus we have a two opposing viewpoints here.
River expects the overarching truth of the universe to make logical sense, and the Bible doesn't do that no matter how you look at it. Book (the guy in the scene) is willing to overlook that because it gives him hope and makes him a better person "you don't fix faith, it fixes you".
Hence, in the context of what you are asking what Bible is... it's not there to give you specifics. It's there to frame the ideals against you can develop PERSONAL SPECIFICS that would be contextualized in these ideals.
You are asking me.... is this verse inspired by God? I have no clue, but I believe that if you read and absorb the entirety of meaning (and not the isolated verse here and there), it formulates and encodes a network of concepts that help us to keep going in a world in a way that has some meaning and hope.
That's really all I can say about it. It may be not satisfactory answer that you are looking for, but I don't have answers in that regard. I can barely communicate meaning, hoping that it doesn't get lost during re-interpretation process.
It's something that you get to look, analyze and decide for yourself. If you already concluded that Bible is a work of men, and is not an accurate portrayal of God... why are you hanging around on a Christian forum? All you'd find is arguments in favor of that idea, given the various models of reality that people hold.