I doubt they gave it a lot of thought when deciding on the cannon. Provenance was more important than content, the 3 synoptics had been in circulation for a long time so they all made it into the book complete with their contradictions. Who was going to argue about it anyway? Dogma was imposed by the educated elite and heretics were not tolerated.
I am not talking about when the authoritive books were canonized but before that, the 200 years before that.
The bible shows no evidence at all of any supernatural input.
Well...even not being a bible inerrantist, I am willing to accept that SOME parts show some "divine" revelation.