All of the above is true hosepipe. Yet we Catholics hold that, on questions of faith and morals, the Vicar of Christ on Earth is infallible.
This is because he, a mere human being, is called and consecrated to the Holy Church that Christ gathers to himself on earth. As occupant of the Throne of Saint Peter, the Holy Spirit constantly attends him, and by His Grace, sees that he is not misled into the snares of untruth.
Picking up on something you've said around here recently, I know you regard the "sheepfold" of John 10 as a sort of "pen" or "prison"; and that you regard this as a metaphor for organized churches. I regard the passage as referring to the place wherein the "sheep" are in maximum safety -- safety from roaming predators, from natural (and unnatural) crises of all kinds....
The Good Shepherd does not want to throw His sheep into the slammer! He wants us to be safe.... And those sheep who know the Voice of the Shepherd, and follow Him, are safe.
Yet as Christ says, "other sheep I have, which are not of this fold: them also I must bring, and they shall hear my voice; and there shall be one fold, and one shepherd."
Evidently, we are not quite there yet....
Actually the sheep form their own sheep pens.. its always been true.. The lord is the gate to the sheep pen.. and he beckons them OUT.. by his voice.. and some follow him, some do not.. the synagogue is also a sheep pen.. Men have a tendency to organize as "clubs".. Its true.. Even within the pens there are cliques.. same is true with the reformed and with the orthodox.. monkdoms and variations of obsession.. i.e. many kinds of Baptist and RCC "groups".... sub-pens..
Is this all thought out (by me)?.. NAH!.. but the metaphor seems to work quite nicely.. And it explains(one explanation) how the Body of Christ can be varied..