"that no prophecy in scripture CAME ABOUT by virtue of some individual's personal exposition or explanation"
Balaam, although not a holy man, is an example of what you are saying. He sure wanted to prophecy curses on Israel for the reward but God moved him to prophecy what He wanted.
Yes, you are correct.
God is the origin of scripture and not some smart dude with robes, a beard, and a wizard's staff.