Most of the Old Testament was originally written in Hebrew, though parts were written in Aramaic, another Semitic language common across the Ancient Near East at the time. The most notable parts are portions of Daniel and Ezra, with suggestions of Aramaic influence in a few isolated verses elsewhere.

The extant New Testament texts are Koine, and I would judge that the majority scholarly consensus is that this represents the form of original composition. Koine was well established as a common trade language in the eastern Roman Empire by the 1st century, and the Old Testament Septuagint text was a century or two old already. In Palestine, Aramaic may have been the everyday language but for the Jewish populations in other cities Greek would easily be the daily language. There are minority views that some of the NT may have been written in Aramaic, and a few early Patristic suggestions that the gospel of Matthew in particular may have been written in Hebrew or Aranaic; there is certainly a Semitic linguistic features in New Testament Koine, but in my opinion the manuscript evidence just isn't there to tenably support fully Hebrew/Aramaic originals. It's more plausible that there may have been early written sources in Aramaic like the hypothesized Q source or a collection of Jesus' sayings without the kind of narrative structure of the four canonical books.

So basically, some early sources might have been Aramaic, and many of the events narrated in the Gospels occurred in Aramaic, but I don't see much support for the actual NT texts being composed in anything but Koine.

Hi, Aramaic translator here. The general modern consensus is that the text of the New Testament was – as we have it today – composed and compiled in Greek, but that it pulled from (and as a result had to translate from) some extant Aramaic source materials in *specific* places (such as the "Q" document materials, the Dialogues layer in the Gospel of John, etc., which show nontrivial signs of Aramaic origins). Sadly those original source layers are lost.