This is a good point. Because it’s not as if we have all documents ever written. Sadly, some get lost over time, and so some beliefs that aren’t represented well (like Assumption of Mary) may have been written about more universally and earlier than thought.
Regardless, this is why we don’t concoct our faith either from the Bible alone, or looking back in history. We have Scripture, Apostolic Tradition, but also that living Tradition expressed even today — through the church’s teaching authority.
Still, as a fun academic exercise, I want to know how people have thought of these things in their own study of history and apologetics.