The writers of the Bible were not concerned with promoting themselves. They would all have agreed with the psalmist who said “Not to us, O LORD, not to us, but to your name be the glory” (Ps 115:1).
They wrote by the inspiration of the one true God (2 Tim 3:16; 2 Pet 1:21), and their concern was to record exactly what God inspired them to record. In a very real sense the author of every book of the Bible was God Himself using human instruments.
This does not mean that the writers of the Bible were like robots or inanimate word processors. God took the writers as they were, with their faults and failings, with their human intellects and emotions and wills, and worked in them and through them to bring His Word into the world, just as He wanted it to be.
God is great enough and wise enough to be able to do this, and He did do it. Men wrote the Bible, but what they wrote came from the mouth of God (Matt 4:4).