Why was the Book of Enoch not included in the Bible? From what I've read, a man of the church- Origen wrote it, and the church condemned it noncanonical because it proves that demons (evil spirits) can take human form via possession.
The Book of Enoch was written long before Origen lived. It was written before the New Testament was written. Possibly one reason most Christian lists of the inspired books do not include the Book of Enoch is that the Jewish teachers did not accept it as part of the Bible. It is not part of what Christians call the Old Testament. The principal objection to the book during the first centuries appears to have been that it claims that angels can sin, and not that they could take human form.
Just the fact that it is quoted in the book of Jude has made some question whether Jude should be included in the New Testament. Paul, however, was known to quote non-scriptural sources, and that did not make people think they were inspired, or his writings less so.
The Ethiopian Orthodox Church does include the Book of Enoch in their canon. They even claim it was originally written in an Ethiopian language, rather than Hebrew, Aramaic, or Greek, because the most complete copy of the book is in the Ge’ez language.