The original languages of both testaments is disputed by scholars, there's evidence both were written originally in Greek (the OT no earlier than 200BC) and translated later into Hebrew, Aramaic, etc. Hebrew was basically a dead language at the time the Old Testament was written, having around 8000 words, and the OT seems to draw heavily from Greek mythological texts available at the time through the Library of Alexandria.

Greek was the lingua franca of the time and Judea, Galilee and Bethlehem were thoroughly conquered at this time and Jesus and the disciples were native Greek speakers. The ruins of synagogues unearthed from the centuries near the crucifixion had Greek text on the walls.

In my opinion, anyone who tries to talk about the Bible but has a lack of understanding of the Grecoroman world is missing 90% of the picture. The most authentic texts are the Greek ones, the Seputagints for the Old Testament and the Greek versions for the New Testament.

Anyone interested in learning ancient Greek is fortunate right now as Dr. Ammon Hillman has a free 2 week intensive course up on his non monetized youtube channel along with a vast amount of supplementary material.