Generally I respect your views, but on this matter I request that you identify your source(s). By the way, there is a lot of good information available on YouTube, despite all the junk.
Whether the book was written by the Enoch of Genesis 5:18-24 is a secondary matter. Many books likely were not written by the person for whom they are named (Esther, Samuel, Titus, Philemon, etc.). That doesn't make them "a lie, or a fiction at best". It is foolhardy to treat as "fiction" every old book that is not part of Scripture, just as it is foolhardy today to ignore modern medical knowledge when you're sick or injured. There is a legitimate distinction to be made between canonical and non-canonical literature, but the latter is not synonymous with "not true"; rather, it simply means "not inspired".