They did the same for the Didache, and the Shepherd of Hermas too.
Some folks didn’t include Hebrews, some didn’t include Jude. There were regional variations on what was considered to be Canon. This wasn’t standardised until St. Jerome compiled and published the Vulgate, and the Canon was set.
Then Martin Luther decided to take parts out he didn’t want. So no one who believes in Sola Scriptura is using scripture in the way that the early church did.
“Paul’s words would include as authoritative Scripture his very own writings as he said to the Galatians that should even an angel declare something contrary to what Paul had passed on to them as good news that one should be accursed. (Gal. 1:6-10)
That’s not what he says.
“But even if we or an angel from heaven should preach a gospel other than the one we preached to you, let him be eternally condemned.”
He does not say that the Epistle of Galatians is to be considered canon. What he does say is the “Preach a Gospel other than the one we preached to you.” Why doesn’t Paul say, “The Gospel written by Luke, or the Gospel written by Matthew?” The answer is that they were not transcribed until after the Epistles were written.
The Gospels were taught orally, from the Apostles who had seen the Risen Lord, to the parishioners. They were first recorded about 25 years after Christ in the synoptic Gospels, which we currently have now, from a combination of interviews and work over quite some time.
The Epistles came first, they were copies of letters that Paul, or Peter wrote to the individual churches. Then after them came the Synoptics, and then finally, the Gospel of John and the Apocalypse.
No. Luther rejected the Apocrypha, as Jerome wanted to do, and for the same reason. There was no binding Church Council requiring otherwise.
The vast majority of the NT was accepted almost as soon as written. But as Protestants tend to point out, no one can make you accept something as scripture.