Comparing the Authorship of the four gospels

Eyewitness testimony is a vital, central evidence to confirm the authenticity of the Bible and establish a real connection with Early Christianity.

Definition of Eyewitness:
1. EY'E-WITNESS, One who sees a thing done; one who has ocular view of any thing.   King James Bible Dictionary/eyewitnesses

2. GREEK: αὐτόπτης, ἀυτοπτου, ὁ (αὐτός, ὈΠΤΩ), seeing with one's own eyes, an eye-witness   Thayers Greek Lexicon/Eyewitness

3. EYEWITNESSES in Greek is autoptai (plural of autopt?s). However, in Luke's preface a historiographical one (history writing). It means those who are first hand observers.   Bible.org/eyewitness

Jesus almost certainly could not speak Greek
Greek was spoken in the two major cities of Galilee (Sepphoris or Tiberius) among the cultured elite.

Jesus was not from a major city or a member of the cultured elite. There is no evidence to indicate he ever travelled to the cities of Galilee, let alone that he was educated or cultured there.

In Nazareth, Jesus would have had no reason to learn Greek, and probably had no way to learn Greek. There is no reference to him ever speaking Greek, or knowing Greek.

Rural Galilee was completely Jewish (culturally) and thoroughly Aramaic (linguistically). Jesus was a rural Jew in the Jewish hinterlands of Galilee. He almost certainly could not speak Greek.

Jesus' customers, if he was a carpenter, stone mason or a blacksmith would have been rural Jews like himself, who spoke Aramaic, not Greek speaking urbanites.   Bart Ehrman, 2012

Irenaeus (130-202 AD) goes on to argue that these four gospels and no others belong in a Christian canon. He is talking about our four Gospels, so they must have existed and even been collected by his time, in the late second century C.E.
Incredible Shrinking Son of Man: How Reliable Is the Gospel Tradition?. Robert M. Price 2003

Because sometime in the second century, when proto-orthodox Christians recognized the need for apostolic authorities, they 'attributed' these books to apostles (Matthew and John) and close companions of apostles (Mark, the secretary of Peter; and Luke, the travelling companion of Paul).

Most scholars today have abandoned these identifications, and recognize that the books were written by otherwise unknown, but relatively well-educated Greek-speaking and writing Christians during the second half of the first century."
Lost Christianities. Bart Ehrman 2003

Justin Martyr (150-160 AD) quotes verses from the Gospels, but does not indicate what the Gospels were named. For Justin, these books are simply known, collectively, as the 'Memoires of the Apostles.'

It was about a century after the Gospels had been originally put in circulation, they were definitively named Matthew, Mark, Luke, and John.

This comes, for the first time, in the writings of the church father and heresiologist Irenaeus, around 180-185 AD."
Forged. Bart Ehrman 2011