I have not come to a conclusion on this issue, but I have a question. How to explain the many times Jesus quoted from the Book of Enoch?

[I have removed the link to a heretical site and quote from it.]

Cera, you are citing a Latter Day Saints (Mormon) website.  These people are heretics who reject the Church's authority and claim that Enoch is inspired Scripture.  That should be setting off warning bells for you. 

Even these people acknowledge that there is only one direct quote from Enoch.  It says "The one direct quote in the New Testament is by Jude, a brother of Jesus Christ." (Note the erroneous claim that Our Lord had a brother.)

The list you have quoted is passages using similar turns of phrase.  This is hardly surprising in works from similar times and cultures.  It is not even strong evidence that Our Lord had Enoch in mind.  Still less does it show that He considered it Scripture.  

Even the Mormon site admits: "It was quoted as scripture by the early Christian Church fathers until the middle of the third century AD, accepted as a divine work having been written by Enoch himself.^[5] It then fell into disrepute and was banned from the canon of scripture in the fourth century," and that "the Book of Enoch was systematically purged from the scriptures until it became a "lost book" of the Bible" until rediscovered in 1773.

The example of the Mormons demonstrates how giving authority to Enoch is associated with rejecting the authority of the Church.  This is exactly why we need to be cautious about how we speak of it and need to be clear about Enoch's lack of authority.

We’ve admitted this, Jaynek, multiple times.  Quit beating a dead horse.

Cera asked a question so I answered it.

In the scriptural annotations, these "Sons of God" do appear as the sons of Seth. The distinction in that passage was between the Elect (professors of true religion) and the Reprobate (professors of error and wicked opinions - false religion). 

The distinction is today between Catholics and Heretics. 

Cera, you are citing a Latter Day Saints (Mormon) website.  These people are heretics who reject the Church's authority and claim that Enoch is inspired Scripture.  That should be setting off warning bells for you.
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The list you have quoted is passages using similar turns of phrase.  This is hardly surprising in works from similar times and cultures.  It is not even strong evidence that Our Lord had Enoch in mind.  Still less does it show that He considered it Scripture. ...

Nice try at "guilt by association," but the quotes from Jesus and the quotes from the Book of Enoch are factual, whatever the source. Facts are facts.
As you well know, it was not a Mormon website -- only a scholar who happens to be a Mormon. Nowhere on his site does it say his religion.
As you must know, translation and re-translation slightly changes the words, leading to what you call "similar turns of phrase." Read with an open mind, it becomes obvious that Our Lord was familiar with the Book of Enoch and often referred to it.
Our Faith teaches us to use reason. Is it reasonable to reject any information from any source because it is Protestant, or it is not Catholic or Traditional Catholic? If so, have you vetted all of your doctors and other professionals, all of your reading material, your news sources? Their facts must be suspect to you.
The facts on Jesus citing the Book of Enoch are widely available from non-Mormon sources. For example here:
https://www.nairaland.com/1080843/book-enoch-jesus-quoted-it
Blessed are the meek, for they shall inherit the earth. (Mat 5:5) The elect shall possess light, joy and peace, and they shall inherit the earth. (Enoch 5:7 {6:9})

the Father judgeth no man, but hath committed all judgment unto the son (John 5:22).
the principal part of the judgment was assigned to him, the Son of man. (Enoch 69:27 {68:39})

shall inherit everlasting life (Mat. 19:29)
those who will inherit eternal life (Enoch 40:9 {40:9})

"Wo unto you that are rich! for ye have received your consolation. (Luke 6:24) Woe to you who are rich, for in your riches have you trusted; but from your riches you shall be removed. (Enoch 94:8 {93:7}).

Ye also shall sit upon twelve thrones, judging the twelve tribes of Israel. (Mat. 19:28)
I will place each of them on a throne of glory (Enoch 108:12 {105:26})

Woe unto that man through whom the Son of man is betrayed! It had been good for that man if he had not been born. (Mat. 26:24)
Where will the habitation of sinners be . . . who have rejected the Lord of spirits. It would have been better for them, had they never been born. (Enoch 38:2 {38:2})

between us and you there is a great gulf fixed. (Luke 16:26)
by a chasm . . . [are] their souls are separated (Enoch 22: 9,11{22:10,12})

In my Father's house are many mansions (John 14:2)
In that day shall the Elect One sit upon a throne of glory, and shall choose their conditions and countless habitations. (Enoch 45:3 {45:3})

that ye may be called the children of light (John 12:36)
the good from the generation of light (Enoch 108:11 {105: 25})

the water that I shall give him shall be in him a well of water springing up into everlasting life. (John 4:14)
all the thirsty drank, and were filled with wisdom, having their habitation with the righteous, the elect, and the holy. (Enoch 48:1 {48:1})

Read with an open mind, it becomes obvious that Our Lord was familiar with the Book of Enoch and often referred to it.

Of course He was quoting Enoch, because the Jєωs considered this book inspired.

And even if Our Lord did read the book of Enoch and use phrases from it, as you imagine, this does not show that He considered Enoch an authority.

At the time of Christ, and for centuries before, it is a historical FACT that the Jєωs considered the book of Enoch as inspired.  This is why Jesus quoted from it, this is why St Jude quoted from it and it is why many of the Church Fathers also used this book to explain the end times.  As has been said already, the book of Enoch was not included as part of scripture NOT because there were problems with Enoch's writings but because such writings had become partially lost and the new translations were not trusted 100%.  (The original texts were probably lost at the destruction of Jerusalem in 70 AD, but that's just a guess).

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There is another theory that it was rejected from the canon as people came to recognize that it was not actually written by the Enoch mentioned in the OT.  

There are few actual facts to work with.  The most pertinent one is that the Church did not include Enoch in the canon and that we should therefore not treat it as authoritative or inspired.

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There is a mountain of ancient writings that are NOT Scripture.
This so-called book of Enoch is just one of them, nothing more.
UFO fanatics and other screwballs like to refer to it to prop up their own faltering legitimacy.

Of course He was quoting Enoch, because the Jєωs considered this book inspired.

At the time of Christ, and for centuries before, it is a historical FACT that the Jєωs considered the book of Enoch as inspired.  This is why Jesus quoted from it, this is why St Jude quoted from it and it is why many of the Church Fathers also used this book to explain the end times.  As has been said already, the book of Enoch was not included as part of scripture NOT because there were problems with Enoch's writings but because such writings had become partially lost and the new translations were not trusted 100%.  (The original texts were probably lost at the destruction of Jerusalem in 70 AD, but that's just a guess).

This. 

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There is a mountain of ancient writings that are NOT Scripture.
This so-called book of Enoch is just one of them, nothing more.
UFO fanatics and other screwballs like to refer to it to prop up their own faltering legitimacy.

Actually, it is those who OPPOSE the UFO fanatics who are using both the Bible and reason to show that what most people believe to be UFOs are actually demonic activity.