Title page from the Ethiopian translation of the Book of Enoch
There was no canon among the first christians. What they had was a couple of scripture collections, called the Law, the Prophets, and the Scriptures. The Scriptures were basically all scriptures that didnt belong to the law and the prophets. Judging from what the ancient jews and the first christians wrote, preserved in their writings, they considered the book of Enoch just as holy, inspired, and doctrinal safe, as the books we now have in the Bible.
It's not unfair to say that huge parts of the New Testament is based on the Book of Enoch.
Much in the letters to the Thessalonians is based on Enoch 62. Those were the first letters Paul wrote. The letter of Jude is based on the book of Enoch, and so are parts of II Peter. When Jesus is talking about the Son of Man sitting on His Throne of Glory, he is referring to several places in Enoch.
Also his woes are similar to those in the Book of Enoch.
This shows that considerable parts of the NT were based on or influenced by the Book of Enoch.
If you go to this website, you can check (and click on) the many parallels between the BOE and the Bible:
It is a well known fact among scholars, so much that before the discovery of the Dead Sea Scrolls, they thought that the book was written after the time of Christ.
If you really study Enoch chapter 62, (and the next chapter) and consider it is written before the letters to the Thessalonians, you will see that Paul not only refers to passages in Enoch 62, but also paints the whole apocalyptic scene from the events in that chapter.
When people read those letters of Paul, they must have recognized it from the BOE. Likewise when Jesus talked about the "Son of Man sitting on His throne of Glory". -Hey, I read that in the book of Enoch! Not to mention Peter and Jude basing whole chapters on Enoch.
The Dead Sea Scrolls were buried not more than 20 km from Jerusalem. The Enoch fragments are in aramaic, hebrew and greek, and written on both papyrus and parchment. The youngest of the DSS are contemporary to the time of the parents of the apostles. Those facts shows the BOE was common knowledge in the time of Jesus. When Jesus talked to the Emmaus-disciples, I'm sure he included the Book of Enoch when he talked about "all the scriptures concerning himself".
I think it is very important to not play down the importance of this book, as it is written especially for the last generation. There will come events that only the book of Enoch can explain. That is the whole point of prophetic messages. Deny them (or cast doubt on them) to your own cost.