Enoch lived 365 years, never died but was taken. His life is recorded to be in and around 3200 BC. His manuscript more than likely kept by his son Methuselah, would have been transferred to Noah who survived the Flood. Noah was the grand-son of Methuselah.
21 When Enoch had lived 65 years, he became the father of Methuselah. 22 After he became the father of Methuselah, Enoch walked faithfully with God 300 years and had other sons and daughters.
25 When Methuselah had lived 187 years, he became the father of Lamech. 26 After he became the father of Lamech, Methuselah lived 782 years and had other sons and daughters. 27 Altogether, Methuselah lived a total of 969 years, and then he died.
Jasher, Chapter 3
11 And Enoch taught them wisdom, knowledge, and the ways of the Lord; and he made peace amongst them, and peace was throughout the earth during the life of Enoch.
12 And Enoch reigned over the sons of men two hundred and forty-three years, and he did justice and righteousness with all his people, and he led them in the ways of the Lord.
13 And these are the generations of Enoch, Methuselah, Elisha, and Elimelech, three sons; and their sisters were Melca and Nahmah, and Methuselah lived eighty-seven years and he begat Lamech.
14 And it was in the fifty-sixth year of the life of Lamech when Adam died; nine hundred and thirty years old was he at his death, and his two sons, with Enoch and Methuselah his son, buried him with great pomp, as at the burial of kings, in the cave which God had told him.
15 And in that place all the sons of men made a great mourning and weeping on account of Adam; it has therefore become a custom among the sons of men to this day.
16 And Adam died because he ate of the tree of knowledge; he and his children after him, as the Lord God had spoken.
17 And it was in the year of Adam’s death which was the two hundred and forty-third year of the reign of Enoch, in that time Enoch resolved to separate himself from the sons of men and to secret himself as at first in order to serve the Lord.
81:5 Then the seven kodesh ones brought me and placed me on the ground in front of the gate of my house, and said to me, “Make everything known to your son, Methuselah, and show to all your children that no one of the flesh can be just before YAHWEH; for they are merely HIS own creation.”
81:6 “We shall let you stay with your son for one year, so that you may teach your children another law and write it down for them and give all of them a warning; and in the second year, you shall be taken away from among all of them.”
82:1 Now, Methuselah, my son, I shall recount all these things to you and write them down for you. I have revealed to you, and given you the book concerning all these things. Preserve, my son, the book from your father’s hands in order that you may pass it to the generations of the world.
82:2 I have given wisdom to you, to your children, and to those who shall become your children in order that they may pass it in turn to their own children and to the generations that are discerning.
83:1 Now, my son Methuselah, I will show you all the visions which I saw, recounting them before you.
83:2 I saw two visions before I got married; and neither one of them resembles the other: The first one I saw when I was beginning to learn books, and the second, before I got married to your mother. First, I saw a scary vision regarding which I prayed to YAHWEH.
106:1 And after some days my son, Methuselah, took a wife for his son Lamech, and she became pregnant by him and bore him a son.
106:2 And his body was white as snow and red as a rose; the hair of his head as white as wool and his demdema beautiful; and as for his eyes, when he opened them the whole house glowed like the sun -rather the whole house glowed even more exceedingly.
106:3 And when he arose from the hands of the midwife, he opened his mouth and spoke to YAHWEH with righteousness.
106:4 And his father , Lamech, was afraid of him and fled and went to Methuselah his father.
106:5 And he said to him, “I have begotten a strange son: He is not like an ordinary human being, but he looks like the children of the malakim of heaven to me; his form is different, and he is not like us. His eyes are like the rays of the sun, and his face aglow.”
106:8 When Methuselah heard the words of his son, he came to us at the ends of the earth; for he had heard that I was there. He cried aloud, and I heard his voice and came to him; and I said to him, “Behold, my son, here I am, why have you come here?”
106:15 “There shall be a great destruction upon the earth; and there shall be a deluge and a great destruction for one year.”
106:16 “And this son who has been born unto you shall be left upon the earth; and his three sons shall be saved when they who are upon the earth are dead.”
107:3 And when Methuselah had heard the words of his father Enoch – for he revealed to him everything in secret – he returned home. And he called the name of that son Noah, for he will comfort the earth after all the destruction.
108:1 Another Book of Enoch – which he wrote for his son Methuselah and for those who will come after him, observing the torah in the last days.
108:2 You who have observed the law shall wait patiently in all the days until the time of those who work evil is completed, and the power of the wicked ones is ended.
108:3 As for you, wait patiently until sin passes away, for the names of the sinners shall be blotted out from the Book of Life and the books of YAHWEH the Kodesh One; …
The Ancient book of Jasher, tells us that Enoch as well as his son Methuselah were High Priests of sorts for all the Kings of the Earth.
Jasher, Chapter 4
2 And when Enoch had ascended into heaven, all the kings of the earth rose and took Methuselah his son and anointed him, and they caused him to reign over them in the place of his father.
3 And Methuselah acted uprightly in the sight of God, as his father Enoch had taught him, and he likewise during the whole of his life taught the sons of men wisdom, knowledge and the fear of God, and he did not turn from the good way either to the right or to the left.
4 But in the latter days of Methuselah, the sons of men turned from the Lord, they corrupted the earth, they robbed and plundered each other, and they rebelled against God and they transgressed, and they corrupted their ways, and would not hearken to the voice of Methuselah, but rebelled against him.
13 And the wife of Lamech conceived and bare him a son at that time, at the revolution of the year.
14 And Methuselah called his name Noah, saying, The earth was in his days at rest and free from corruption, and Lamech his father called his name Menachem, saying, This one shall comfort us in our works and miserable toil in the earth, which God had cursed.
15 And the child grew up and was weaned, and he went in the ways of his father Methuselah, perfect and upright with God.
16 And all the sons of men departed from the ways of the Lord in those days as they multiplied upon the face of the earth with sons and daughters, and they taught one another their evil practices and they continued sinning against the Lord.
17 And every man made unto himself a god, and they robbed and plundered every man his neighbor as well as his relative, and they corrupted the earth, and the earth was filled with violence.
18 And their judges and rulers went to the daughters of men and took their wives by force from their husbands according to their choice, and the sons of men in those days took from the cattle of the earth, the beasts of the field and the fowls of the air, and taught the mixture of animals of one species with the other, in order therewith to provoke the Lord; and God saw the whole earth and it was corrupt, for all flesh had corrupted its ways upon earth, all men and all animals.
19 And the Lord said, I will blot out man that I created from the face of the earth, yea from man to the birds of the air, together with cattle and beasts that are in the field for I repent that I made them.
20 And all men who walked in the ways of the Lord, died in those days, before the Lord brought the evil upon man which he had declared, for this was from the Lord, that they should not see the evil which the Lord spoke of concerning the sons of men.
21 And Noah found grace in the sight of the Lord, and the Lord chose him and his children to raise up seed from them upon the face of the whole earth.
Jasher, Chapter 5
22 In that time, the Lord said to Noah and Methuselah, Stand forth and proclaim to the sons of men all the words that I spoke to you in those days, peradventure they may turn from their evil ways, and I will then repent of the evil and will not bring it.
23 And Noah and Methuselah stood forth, and said in the ears of the sons of men, all that God had spoken concerning them.
34 In his five hundred and ninety-fifth year Noah commenced to make the ark, and he made the ark in five years, as the Lord had commanded.
35 Then Noah took the three daughters of Eliakim, son of Methuselah, for wives for his sons, as the Lord had commanded Noah.
36 And it was at that time Methuselah the son of Enoch died, nine hundred and sixty years old was he, at his death.
6:3 And the Lord said, My spirit shall not always strive with man, for that he also is flesh: yet his days shall be an hundred and twenty years.
6:5 And God saw that the wickedness of man was great in the earth, and that every imagination of the thoughts of his heart was only evil continually.
Just before the Flood, God decreed that Man shall thereafter only live to be 120 years old.