You are going to argue that the original NT was not written in Koine Greek LOL?!?!? Uh, OK...knock yourself out!
It was casually mentioned that there was a tradition that the original Matthew "may" have been in Aramaic. Nobody knows if it was originally in Hebrew or translated from the Greek or if it ever existed.
Around 180 AD Irenaeus of Lyons wrote that Matthew also issued a written Gospel among the Hebrews in their own dialect. (Against Heresies 3:1:1)
Fifty years earlier Papias, bishop of Hieropolis in Asia Minor, wrote that Matthew compiled the sayings of the Lord in the Aramaic language, and everyone translated them as well as he could. Explanation of the Sayings of the Lord (cited by Eusebius in History of the Church 3:39).
Sometime after 244 AD Origen wrote, "Among the four Gospels, which are the only indisputable ones in the Church of God under heaven, I have learned by tradition that the first was written by Matthew, who was once a publican, but afterwards an apostle of Jesus Christ, and it was prepared for the converts from Judaism and published in the Hebrew language." Commentaries on Matthew (cited by Eusebius in History of the Church 6:25)
Eusebius himself declared that Matthew had begun by preaching to the Hebrews, and when he made up his mind to go to others too, he committed his own Gospel to writing in his native tongue (Aramaic) History of the Church 3:24