In fact David is called a prophet though he could not know exactly how or what the outworking of what he prophesied would be.
But saying, “One is verbatim; the other is the best interpretation of the inspired individual.” is the far end of the spectrum of the influence of holy spirit, it seems to me.
They were originally included in the Tanakh, which the Jews recognized as lesser Scripture. The Church used the Septuagint as OT Scripture, and eventually authorized the new writings of its choosing as NT Scripture. However, nowhere does the NT claim that God dictated it; the closest we come is the quotations of Jesus.