Firstly, it says Jude is quoting Enoch, not the book of Enoch. That's a big difference. This is what Jude says:
Jude 1:14-15
It was also about these that Enoch, the seventh from Adam, prophesied, saying, Behold, the Lord comes with ten thousands of his holy ones,
to execute judgment on all and to convict all the ungodly of all their deeds of ungodliness that they have committed in such an ungodly way, and of all the harsh things that ungodly sinners have spoken against him.
And this is what Enoch 1:9 says:
"And behold! He cometh with ten thousands of His holy ones to execute judgment upon all, and to destroy all the ungodly: and to convict all flesh of all the works of their ungodliness which they have ungodly committed, and of all the hard things which ungodly sinners have spoken against Him."
As you can see it is not an exact quote. You might say close enough, but close enough doesn't cut it. If you want to accuse Jude of bad quoting, then you are also accusing the Holy Spirit. The more likely possibility is that this statement is something handed down from Jewish oral tradition, and it also ended up in the book of enoch. You also have to remember that Jude was inspired by the Holy Spirit. He could easily quote Enoch directly, just like Moses quoted Adam and Eve without being there. The main point is that just because this quote appears in both texts doesn't mean there is a connection or that Enoch is inspired.
There are a few errors in the book of Enoch. For instance, Enoch is recorded in Genesis to be born about 622 years after the creation of the world. He lived 365 years before God took him.
Genesis 5:23-24
23 So all the days of Enoch were three hundred and sixty-five years. 24 And Enoch walked with God; and he
was not, for God took him.
Yet, the book of Enoch gives an account of Noahs birth. It has Enoch telling Methuselah ""'And now, my son, go and announce to thy son Lamech, that this son who is born is really his, and that this is not a falsehood.'"
And when Methuselah had heard the words of his father Enoch -- for he had shown him everything that was secret -- he returned, after his having seen him, and called the name of that son Noah, for he will make glad the earth for all destruction"
The problem with this account is that Noah was born around 1056, about 70 years after Enoch departed, according to Genesis.
The book of Enoch has angels marrying women on Earth, but scripture says:
For when they rise from the dead, they neither marry nor are given in marriage, but are like angels in heaven"
The Book of Enoch states that sin came from the intermixing of angel seed and man's seed.
The bible says sin came into to the world by the sin of Adam:
Therefore, just as through one man sin entered the world, and death through sin, and thus death spread to all men, because all sinned"
Chapter 22 of the Book of Enoch has the realm of the dead divided into four areas: 1) Righteous martyrs, such as Abel, 2) The righteous who were not martyrs, 3) sinners who died without suffering the consequence of their sin, and 4) sinners who had suffered as the result of their sin
Of group 4 Enoch says this: "but their spirits shall not be slain in the day of judgment nor shall they be raised from thence"
This contradicts the bible in two places.
1. The bible says the realm of the dead is divided into two, not four:
Luke 16:19-31
2. The bible also says that all will raised and face judgement
"
Do not marvel at this; for the hour is coming in which all who are in the graves will hear His voice and come forth --those who have done good, to the resurrection of life, and those who have done evil, to the resurrection of condemnation"
It also contradicts itself:
Enoch 6:7-8 gives a list of the leading fallen angels: "And these are the names of their leaders: Samlazaz, their leader, Araklba, Rameel, Kokablel, Tamlel, Ramlel, Danel, Ezeqeel, Baraqijal, Asael, Armaros, Batarel, Ananel, Zaqiel, Samsapeel, Satarel, Turel, Jomjael, Sariel."
The list repeats:
Enoch 69:2-3, "And behold the names of those angels [and these are their names: the first of them is Samjaza, the second Artaqifa, and the third Armen, the fourth Kokabel, the fifth Turael, the sixth Rumjal, the seventh Danjal, the eighth Neqael, the ninth Baraqel, the tenth Azazel, the eleventh Armaros, the twelfth Batarjal, the thirteenth Busasejal, the fourteenth Hananel, the fifteenth Turel, and the sixteenth Simapesiel, the seventeenth Jetrel, the eighteenth Tumael, the nineteenth Turel, the twentieth Rumael, the twenty-first Azazel."
The first list has nineteen names, the second has twenty-one, and many are very different.
So, while I understand the book of Enoch is interesting, it was not inspired by God. No Christian should be looking to it as any sort of truth. As with everything Satan does, it contains half-truths (the bait) and then outright lies.