“The impact of this on belief cannot be overstated. If the early Church hadn’t believed that these books came from eyewitnesses and their first-generation disciples, the books would not have been accepted into the Canon.”
In studying the decision-making process of the canon - originally and subsequently through many iterations - ascribed authorship that was believable counted for a lot. It was not everything Mrs. Don-o. There are books without certainty of authorship - Hebrews comes to mind. There are things Apostles wrote that were not inspired and not included.
I commend to you the study of the canon process. As with much of our history, it is messy. God worked through it. Some errors crept in anyway and were corrected later.
For those reasons, when you read one of the four gospels today, you do not have to believe the authorship. Nor is it necessary to believe it for the words to be true.
Seriously, it surpasses good sense to think the Church canonized non-inspired books. If it had, even her reliability in canonizing the correct ones would have been fatally undermined. The whole thing would have been debatable and up for grabs: hurricane hits a double-wide.