Primary role was to supply God’s direct commentary on how contemporary people were measuring up to the Mosaic covenant standards. Prophetic messages were unoriginal; never spoke on their own. Their voice was always ignored, persecuted, or both. In short, they changed nothing and no one.
Prophets did predict the future at times, yet usually the immediate future. Many prophecies that address the future do not separate events in detail. Less than 2% of Old Testament prophecy is messianic, less than 5% specifically describes the New Covenant, and less than 1% foretells a time beyond ours.
Major Prophetic Books (Isaiah, Jeremiah, Ezekiel, Daniel) vs. Minor Prophetic Books (the remaining 12) are distinguished by length, not significance. Ancient Judaism clustered the minor prophetic books into one book called “The Book of the Twelve.”