“to pass down revealed truth, unadulterated and unchanged for two thousand years.”
Now that’s funny not really, but it is and absolute lie! How many councils has your denomination had, apporx 21? Most of them changed fundamental beliefs thus your claim is built on a lie. I will give you a couple as examples do your research you have been boondoggled.
1245AD - 1st Council of Lyons
1274AD - 2nd Council of Lyons
Discussed and formulated the official church position on purgatory.
1545-1563 - Council of Trent
Cannon 6, The establishment of the 7 sacraments for salvation not by Grace alone.
These changes are MAJOR doctrine changes as both refer to eternal life one way or the other. I have just cited two examples there are so many more. One example took over 1200yrs and the other over 1500yrs. Sorta odd that they were passed down, but took that long to become “Official” doctrine.
But Rome autocratically defines what a contradiction is, and what RCs will argue, and can have merit, is that what you are referring to is conciliar affirmations or definitions (if not always infallible) of what was believed before.
But which does not mean it was believed everywhere and by all, or even close to that. And it can even mean it lacking in actual early evidence. Rome can just claim to remember what she "forgot."
Listen to Ratzinger explain the Assumption, which is lacking in early evidence:
Before Mary's bodily Assumption into heaven was defined, all theological faculties in the world were consulted for their opinion. Our teachers' answer was emphatically negative...
Altaner, the patrologist from Wurzburg…had proven in a scientifically persuasive manner that the doctrine of Mary’s bodily Assumption into heaven was unknown before the 5C; this doctrine, therefore, he argued, could not belong to the “apostolic tradition. And this was his conclusion, which my teachers at Munich shared. This argument is compelling if you understand “tradition” strictly as the handing down of fixed formulas and texts…
But if you conceive of “tradition” as the living process whereby the Holy Spirit introduces us to the fullness of truth and teaches us how to understand what previously we could still not grasp (cf. Jn 16:12-13), then subsequent “remembering” (cf. Jn 16:4, for instance) can come to recognize what it has not caught sight of previously and was already handed down in the original Word,” J. Ratzinger, Milestones (Ignatius, n.d.), 58-59.
Yes, tradition certainly was conceived to teach this, "remembering" what was is wanted, making it a binding doctrine no less, but to attribute this to the Holy Spirit is blasphemous and makes Rome a false teacher, teaching for doctrines the traditions of men. For which she will suffer.
In contrast,
For we have not followed cunningly devised fables, when we made known unto you the power and coming of our Lord Jesus Christ, but were eyewitnesses of his majesty. (2 Peter 1:16)