Even if the protestants call the Church fathers utterly ignorant; if they accept the body of scripture they created (which most do) they amit that they had an undeniable presence of the Holy Spirit, something which they have never managed to establish in their churches (where any decision 'in the holy spirit' is subject to a subsequent reversal 'in the holy spirit'.
Quite beside the role of the Church in creating and sorting out the scripture, no one would have believed Christ is it were not for the martyrs of the Church that gave the Word to the world by dying for their faith. It was not an intellectual exercise then; it is not an intellectual exercise now.
I can tell you what Christianity would have been without the witness of the saints of the Church: an intriguing but largely unworkable ethical system taught by a lunatic, whose followers had a large imagination. We'd pay more attention to Seneca than to Christ if He chose to leave us with the scripture alone.
Is it a tenet of Protestantism that the hierarchs who determined most of the canon of scripture you study were merely performing a sort of automated housekeeping project, ...
In my view, God ALONE determined what would be, and would not be in scripture. He alone caused it to be correctly written, determined within early practicing churches, and finally assembled formally according to His exact specifications. All those involved acted precisely as God had preordained it from before time. That would be the only way to ensure that the scriptures are not only inerrant, but perfect. The scriptures are God's revelations to His most beloved on earth. How could they be any less than perfect?
Yes, there are squabbles about translations and the Apocrypha, and such, but those are squabbles among men. I don't think that touches the idea that God DID, in fact, lay down one complete and perfect scripture. I would be fairly sure that none of us has a letter for letter copy of it. IMO, the vast majority of the problems come from interpretation, not translation.
... understanding little if anything of what they were reading, persisting as they did in their "unscriptural" liturgies and ecclesial structure, venerating icons, praying to saints, etc. ...
I have no idea how much the Fathers of that time understood, or didn't. I can't name a post, but I thought you had agreed earlier that in the first days the structure of the early Christian churches and the worship that was actually practiced was not at all under an "iron fist", as some would refer to it today. (Of course, this is much more so in Catholicism.) That would seem to leave open a lot of questions as to just how many actual Christians practiced the things you listed above.
In addition, the Bible is littered with examples of just how fast God's people turned against Him. The various experiences of Moses are one example. I make no comparison in degree, but merely point out that just because somebody does something "soon after" doesn't make it right by definition.
... so that, 1100+ years later, a few Western European guys angry at the medieval Papacy would finally and at long last sort of understand what was necessary for salvation and that from that "sort of" level of understanding arises the at long last harmonious theology of 21st century Protestantism?
Well, I think there is a debate on just when Reformed beliefs "started". Remember how many Patristic writings you have been so kind to show me I have found favor with? I figure there has to be a reason for that. I suppose it may go back to the interpretation of the interpreters. I do not at all think that my theology was "born" with the advent of the original Reformers. Those original Reformers were just the most famous ones to make a federal case out of it. :)