1st, what language did Christ speak, Aramaic, Hebrew, not Greek, therefore the Greek would be a translation of the oral spoken word.
Two from early church fathers we know that Mat was originally written in Hebrew/Arameic
Mark who wrote the Gospel, which he [Papias] has given in the following words]: And the presbyter said this. Mark having become the interpreter of Peter, wrote down accurately whatsoever he remembered… **Matthew put together the oracles [of the Lord] in the Hebrew language **(Papias of Hierapolis Fragments from the Exposition of the Oracles of the Lord 90 AD) Chap IX
Matthew also issued a written Gospel among the Hebrews3 in their own dialect, while Peter and Paul were preaching at Rome, and laying the foundations of the Church. After their departure, Mark, the disciple and interpreter of Peter, did also hand down to us in writing what had been preached by Peter. Luke also, the companion of Paul, recorded in a book the Gospel preached by him. Afterwards, John, the disciple of the Lord, who also had leaned upon His breast, did himself publish a Gospel during his residence at Ephesus in Asia.(Irenaeus of Lyons Against Heresies Book III Chap I 180 AD)
" In his[ie. Origen] first book on Matthew’s Gospel, maintaining the Canon of the Church, he testifies that he knows only four Gospels, writing as follows: 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. The second is by Mark, who composed it according to the instructions of Peter, who in his Catholic epistle acknowledges him as a son, saying, ‘The church that is at Babylon elected together with you, saluteth you, and so doth Marcus, my son.’ And the third by Luke, the Gospel commended by Paul, and composed for Gentile converts. Last of all that by John." Origen,Commentary on Matthew,fragment in Eusebius Church History,6:25,3(A.D. 244),in NPNF2,I:273