The Gospel of Matthew is written in Greek, not in Aramaic. The Greek of the gospel of Matthew cannot easily be translated back to Aramiac. This is very suggestive that Matthew is not a Greek translation of an Aramiac original. It is also generally agreed that the Gospel of Mark is actually the earliest of the four gospels and that the author of Matthew substantially used the gospel of Mark in writing this gospel.
A minority of scholars defend the tradition that asserts Matthean priority, with Mark borrowing from Matthew (cf. Augustinian hypothesis and Griesbach hypothesis). Then in 1911, the Pontifical Biblical Commission asserted that Matthew was the first gospel written, that it was written by the evangelist Matthew, and that it was written in Aramaic.
For convenience, the book can be divided into its four structurally distinct sections: Two introductory sections; the main section, which can be further broken into five sections, each with a narrative component followed by a long discourse of Jesus; and finally, the Passion and Resurrection section.