There are several reasons why the book of Enoch is not in the Bible. One reason is that you can conclude from the book that all people were black before the Flood.
How?
Lamech (and his family) was very surprised by the look of his son(noah) at birth, because he had white skin. He had never seen a white human, since they did not exist. But Noah was not an ordinary white man, he was an albino.
Because lamech was so surprised by his son's look, and he has never seen a white huma before, we can conclude that all humans were black before the Flood and that all Noah's children were black as well. So if all Noah's children were black, how can it be that the Messiah is white? Jesus must have a black skin. So it could be racism, maybe the church fathers couldn't bear that the Messiah is black and therefore didn't keep the book of Enoch in the Bible.
But that is not all. One now asks oneself the justified question where the white people come from.
The book Enoch tells us not only that the people before the Flood were black but also that the children of the angels(nephilim) and the angels themselves were white. Lamech said when he saw Noah for the first time: His looks like one of the angels of God - so the Nephilim and also the angels are white. The white people are the descendants of the Nephilim.
Enoch 106
1 And after some days my son Methuselah took a wife for his son Lamech, and she became 2 pregnant by him and bore a son. And his body was white as snow and red as the blooming of a rose, and the hair of his head and his long locks were white as wool, and his eyes beautiful.(albino) And when he opened his eyes, he lighted up the whole house like the sun, and the whole house 3 was very bright. And thereupon he arose in the hands of the midwife, opened his mouth, and conversed with the Lord of righteousness. 4 And his father Lamech was afraid of him and 5 fled, and came to his father Methuselah. And he said unto him: ' I have begotten a strange son, diverse from and unlike man, and resembling the sons of the God of heaven; and his nature is different and he is not like us, and his eyes are as the rays of the sun, and his 6 countenance is glorious. And it seems to me that he is not sprung from me but from the angels, and I fear that in his days a wonder may be 7 wrought on the earth. And now, my father, I am here to petition thee and implore thee that thou mayest go to Enoch, our father, and learn from him the truth, for his dwelling-place is 8 amongst the angels.' And when Methuselah heard the words of his son, he came to me to the ends of the earth; for he had heard that 1 was there, and he cried aloud, and I heard his voice and I came to him. And 1 said unto him: ' Behold, here am I, my son, wherefore hast 9 thou come to me ? ' And he answered and said: ' Because of a great cause of anxiety have I come to thee, and because of a disturbing vision 10 have I approached. And now, my father, hear me: unto Lamech my son there hath been born a son, the like of whom there is none, and his nature is not like man's nature, and the colour of his body is whiter than snow and redder than the bloom of a rose, and the hair of his head is whiter than white wool, and his eyes are like the rays of the sun, and he opened his eyes and 11 thereupon lighted up the whole house. And he arose in the hands of the midwife, and opened 12 his mouth and blessed the Lord of heaven. And his father Lamech became afraid and fled to me, and did not believe that he was sprung from him, but that he was in the likeness of the angels of heaven; and behold I have come to thee that thou mayest make known to me the truth.
