What, infallibility wasn't decreed retroactive? I'm shocked. Yes, men are fallible. Inspired scripture is not. That's why we need it, and not men running amok without such an immovable anchor to truth. Otherwise, they'd start imagining themselves infallible, start prancing around in ermine gowns and slippers, and just generally making asses of themselves.
Oh, wait ...
Scripture doesn’t self-decree the canon. Many early Christians, for example, regarded Revelation and Hebrews as apocryphal.