Apparently you are not reading the various posts. Go check the posts that were sent to ealgeone on the second Pope- Pope Linus in AD 67-76 and check out the line of succession. Of course, no one accepts you to consider this as proof even if a broad spectrum of distinguished historians, scholars, and theologians have done so including several such Protestants who converted to Catholicism.
What is apparent, is that many non-Catholics fish out of a pool of ant-Catholic diatribe written by folks, arm-chair internet theologians, whose works have never been peer evaluated for their historical authenticity but rather by stringing together disparate quotes and writings.
Even the early Church had discussions, disagreements and debates and these were finally settled by the doctrine of infallibility as given by Christ to Peter. This is a historical truth. To Elsie, this is all evidence of “confusion,” just as often as non-Catholics are hopelessly confused about the lives of individual popes with formal doctrine.
As Legatus doesn't want a wall of text I refer to the link.
Elsie has posted the comments from the ECFs that differ with catholicism on this issue.
If something were so clear as steelfish alludes to there wouldn't be this many disagreeing sources.
I'll say this. Keep your focus on Christ and you won't go wrong. Worship Him only. Rely upon Him only.
Too bad the conversations that John had with angel; as recorded in Revelation chapters 1 thru 3; completely blow the 'infallibility' thing right out of the water!