Gen 5 is a genealogy of the descendants of Adam through his third son, Seth. There is a particular formula: so-and-so lived x years and sired such-and-such. After siring such-and-such, so-and-so lived y years and sired sons and daughters. The total number of days of so-and-so's life was x+y years, and he died. There is one exception: Gen 5:21-24 speaks of Enoch (חנוך). We are told that once Enoch had lived 65 years, he sired Methuselah, and after doing so "he walked with God" for 300 years, siring sons and daughters. The total number of years of Enoch's life were 365 and then "he was no more, for God took him".
What strange terminology! While everybody else simply lives their lives, Enoch does his walking with God; while everybody else simply dies, Enoch is taken by God and is no more. What are we to make of this? A quick look at some other traditions concerning Enoch will shed light on what the Enoch tradition may actually involve.
The first place to look would be the Books of Enoch themselves. Of these, 1 Enoch (also, 'Ethiopic Enoch') is the most relevant for our purposes, although 2 Enoch (also, 'Slavonic Enoch') and 3 Enoch belong within the tradition as well. These texts treat Enoch as a hero of sorts, alongside heroes like Noah and Adam. These three figures have received very little attention outside of the 'Enoch tradition' as they feature prior to the exclusivity of the covenant tradition. God's covenant with Abraham, which takes its strongest shape after Moses' reception of the Law, is not in effect prior to the flood. For that reason, traditions such as those which revered Enoch may have become marginalised after the normalisation of Rabbinic Judaism.
Another reason for this may be the terminology employed in the narrative. Where I have here translated "walked with God", the Hebrew reads "ויתהלך חנוך את־האלהים". Elohim is a word that could be translated in a variety of different ways. Where it refers to God, it generally takes a singular verb (although not always: witness Gen 1:26) but, as it serves here as the object of the verb, we have no way of knowing if God is indeed the referent. The Enoch tradition (typified mainly by 1 and 2 Enoch, as well as Jubilees and 1QapGen) understands אלהים to mean "gods". They may even be a reference to the giants that roam the earth in Genesis 6:1-7 - another theme to feature strongly in Enochic literature.
The assertion that Enoch had little to no appeal in Jewish circles is testified to in the unpopularity of Enoch in later Jewish traditions. While 1 Enoch may have been very popular at Qumran (as was Jubilees, a work that appears to revere Enoch as the founder of the calendar), it was not popular elsewhere. Aramaic translations of the Bible ('targumin') refer rather dismissively to Enoch. Onkelos says that, at the end of his life, Enoch "was not, for God killed him", and various other translations (such as Neofiti, Fragmentary Targum msV and Pseudo-Jonathan) present this idea as well.
The Midrash is explicit. Genesis Rabba 23:6 states that humanity was only in the image and likeness of God until the generation of Enosh (Enoch's great-great-grandfather), after which the generations successively worsened and produced destroyers (which is probably a reference to the giants of 6:1-7). Genesis Rabba 25:1 even goes so far as to declare that Enoch was a hypocrite - sometimes righteous, sometimes wicked - until such time as God removed him from the earth and wrote his name in the scroll of the Wicked. Two short stories follow, the purpose of both of which is to emphasise the fact that Enoch truly died. Enoch is not mentioned so much as once in the entire Talmud.
In the New Testament, however, Enoch receives a facourable report in both Hebrews 11:5 and Jude 1:14-16, not to mention the Christian "Testament of Levi", chapters 14 and 16. The apocryphal Jesus ben Sirakh ("Ecclesiasticus") sees Enoch as a model of repentance for all generations (44:16). Why was Enoch detested by the Jews? The answer may become apparant if we have a look at Jubilees 4:17-23. There, Enoch is credited with the development of the calendar (amongst other things). Many of these things (writing and knowledge and wisdom) are ascribed to the giants in Midrash Avkir. This conflation of roles may indicate that Enoch was perceived as one of the "destroyers", alongside the giants themselves.
Jubilees is also famous for being a work that emphasises a solar calendar - indeed, much the the book is effectively a polemic against those who utilise the moon in calendrical observations. Some scholars have argued, on the basis of the utilisation of dates in the Pentateuch, that the Israelite calendar was initially a solar calendar, and that the luni-solar calendar of the Pharisees was a corruption of the same (cf: Ellis Rivkin, "The Book of Jubilees - An Anti-Pharisaic Pseudepigraph?", ארץ ישראל v16, 1982 - pp193*-198*). A quick comparison of Enoch with the other antediluvian patriarchs may indicate that the connection between Enoch and the solar calendar was well known. The following is a list of Adam and his descendants, up until the flood, with the age at which they died written alongside.
Adam - 930
Seth - 912
Enosh - 905
Kenan - 910
Mahalalel - 895
Jared - 962
Enoch - 365
Methuselah - 969
Lamech - 777
Noah - 950
None of the ages of the other individuals appear to represent anything. Enoch, however, with his 365 years, appears to match up to the solar calendar exactly. Well, not exactly. Jubilees suggests 364 days to the year (Jub 6:32). Some have suggested that the author of Gen 5 is deliberately subverting the Enoch tradition but, even if that's the case, it proves the existence of the tradition nonetheless.
While we have had occasion to note that Enoch is not mentioned so much as once in the Talmud, a statement made by Pseudo-Jonathan in his Aramaic translation of Genesis is relevant here. He argues that when Enoch ascended to heaven, he became an angel named Metatron (מיטטרון). This is also reflected in 3 Enoch 4:2 - another late Jewish text (no earlier than 100 CE). There are different theories concerning the provenance of this name, one popular one being that it is the conjunction of two Greek words, μετα and θρονως, and that it literally means, 'alongside the throne'.
Whether or not this is the case, Metatron's role within the Rabbinic tradition is an entirely passive one, serving effectively as the mouthpiece of God. This subversion of the Enochic tradition is the means by which the Rabbis allow the tradition to live on, albeit in a thoroughly harmless way. Such may also have been the intentions of the author of the genealogy in Genesis: to include references to Enoch and the giants, but to render them meaningless within the broader tradition. As Michael Stone noted,
"...there is no reason to think that the body of literature that is transmitted as the Hebrew Bible is a representative collection of all types of Jewish literary creativity down to the fourth century. It is a selection of texts and the process of transmission and preservation that created this selection reflects the theological judgement of certain groups"Selected Studies in Pseudepigrapha and Apocrypha: With Special Reference to the Armenian Tradition (Leiden: E.J. Brill, 1991), pp195-196.