This is a subsidiary post of The Formation of the New Testament…from Beginning to End.
The mere existence of the NT implies editorial activity as well as authorial activity. There the collection of writings is before you. If each of the 27 writings had its own unique origin, what was the origin of the collection of these writings?
The authors names are given. If you think information about the authors is meager, consider how much more meager is information about the editor(s).
That the NT is a collection of (4) smaller collections has a bearing on the titles and the order of the books.
Some editorial activity is lost when the NT is put together – e.g. the titles of the 4 collection units.
To understand the NT as a collection you have to go outside of the NT. Yes, there are seeds of the NT canon to be found in the NT, but the study cannot be completed without referring to post-1st-century history.
More on Specific Editorial Activities
Consider also The Study of Canon and the Etymology of Certain Terms, which are, of course, related to the formation of the New Testament.