“If not what book or books did they miss?”
Early on, Barnabus, Clement and The Shepherd at least. But your point is a good one, though better made, I think, in your earlier post. The fact is, however, that there were all sorts of writings floating around back then and people were reading them. Now we look back and say that the HS guided people correctly without a council to determine the canon. Well, yes and no. The early Church, what +Ignatius of Antioch called the “catholic” church, is what survived as an “institution” in various forms, Orthodoxy and Oriental Orthodoxy in the East and the Church of Rome and its children the “Protestant” churches in the West. All Trinitarian groups or churches which call themselves Christian descend from or in fact are that One Church. The other groups fell away into self destroying heresy for the most part. It therefore stands to reason, wf, that when we look back at what our spiritual forebears were reading we would see pretty much what we have today because it was “our people” (meaning pretty much all of us here) who made the determinations based on a certain definite set of beliefs.
I would agree with the caveat that it was the Holy Spirit that was directing them. I believe this to be the case because if it were solely accomplished by the will of one like minded group in 1800 years we would have found books that clearly should have been included and books that should not have been included.
BTW, I do like your description of the early church. I think the different churches that left, or never became a part of the dominant church is a natural result of centralized authority.