The four gospels were written, borrowed and redacted by people with their beliefs. It's based on narratives that were circulating in communities of believers. It's not something that came from outside of community.
Can you give an example of books that were discarded and destroyed? Or any evidence about this?
Some of them are
1 Esdras
2 Esdras
Tobit
Judith
The rest of Esther
The Wisdom of Solomon
Ecclesiasticus
Baruch with the epistle Jeremiah
The Songs of the 3 Holy children
The history of Susana
bel and the dragon
The prayer for Manasses
1 Maccabees
2 Maccabees
However I have a bible that includes the Books of the Apocrypha
The Ethiopian and Coptic bibles also have a different set of Books included in their bible canons.
We know there were other texts rejected in the earlies bibles because some were mentioned in other documents.
And they hardly set up a Synod to do nothing. they were selective what they included.
As was the catholic Cull in the 4th and 5th centuries.
The Bible canon has changed over time.
most of the changes are well documented if you care to look into it further.
You will find that all the Gnostic Gospels and writings have been excluded such as the Gospel of Mary and the Gospel of Thomas.
There is more stuff excluded that ever found its way into the Bible.