All of the Bible was written by Torah-observant Jews
shalom b'SHEM Yah'shua
( except for the doctor Luke who was gentile)
under the guidance of the Ru'ach HaKodesh.
How do you know who wrote these books, since the text does not name the author? We also do not know the time nor the place nor the occasion for their writing, nor their authority, save by testimony of the Church. You may rightly question only what is meant by the Church and when or where they chose to canonize these Scriptures. Given the content of theser writings is likely that they were, as you say, Torah observant Jews—save “Luke-Acts,”—but then we must ask, for what purpose except to tell us what is meant by Torah.