Same thing that changed between the Canons of The Council of Orange and Trent.
Widespread corruption and various abuses that triggered The Reformation. When Luther and company called foul Rome, out of pride and greed, pushed back with new errors. And as a result now we have Trent and the Deuterocanonical books.
From the church that never changes, eh?
Same as it was in the first century?
I think not.