Here's what William Kelly says on Jude 1 -
[quoting]
"But how was Jude enabled to quote the words of Enoch, who was taken up to heaven before the flood - and nothing can be plainer than that he does give it as Enoch's words? "Enoch prophesied," he says. Well, I think that to us who know the power of the Spirit of God there is no real difficulty in the matter. It is all the same to Him to record what took place three thousand years ago as it would be to record what took place at the time the apostles lived. It may be a little more difficult to those who doubt this power, if they do; but we are the last who ought to do so.
"The fact is, that no tradition has any value beyond man, but a prophecy necessarily, if it is a true one, comes from God. We have no intimation that it was conveyed in any written form, and it was quite possible for the Holy Ghost to have given it again to Jude. I do not at all venture to say that it was so; we really do not know, but we do know, however Jude got it, that it is divine. We know that it is given with absolute certainty, and that it possesses God's authority.
There is a peculiarity when it says, "Enoch also, the seventh from Adam." People have made somewhat of that because they do not understand it. But it is very simple. There was more than one Enoch.
"There was an Enoch before this one - an Enoch the son of Cain. I do not see any ground to imagine something peculiar and mystical in this. At any rate, if there be such, I confess I do not know what it is. But I do know that there is a plain and sufficient sense to distinguish this Enoch, and to explain how he could prophesy. We should not look for prophecy in a son of Cain. But that Enoch taken up to heaven in a most remarkable way - more so, in some respects, than the case of any other man; more so than Elijah, though that was a miracle of similar import and character - that Enoch should be the medium of prophecy we can quite understand, for he walked with God, and was not. It was not that he died, but "he was not," because he was taken up to God; yet before he left the world, he prophesied. We can hardly doubt that he prophesied about the people of his own day. Prophecy always takes its start from what is actually present, and has a hold in the consciences of those then living. The object was to warn of the terrible consequences of evil that was persisted in, and how the evil then appearing would assuredly be judged of God in due time. But the Spirit of God also launches out to the end from the beginning. This is the common character of all prophecy. We find it throughout all the prophets at any rate. I do not, of course, say that it was always the case where the prediction was about something of a merely present nature, but it was so in the cases of those moral pictures which are not bound to any particular time or person. We can quite understand these being made the vehicle for the Spirit of God to look on to the time of judgment when it would not be providential action of the Lord, such as the flood, for instance, but - much more than any acting after that figurative manner - His real personal coming in judgment."
--William Kelly, Jude 1
[end quoting; bold mine]
[quoting]
"But how was Jude enabled to quote the words of Enoch, who was taken up to heaven before the flood - and nothing can be plainer than that he does give it as Enoch's words? "Enoch prophesied," he says. Well, I think that to us who know the power of the Spirit of God there is no real difficulty in the matter. It is all the same to Him to record what took place three thousand years ago as it would be to record what took place at the time the apostles lived. It may be a little more difficult to those who doubt this power, if they do; but we are the last who ought to do so.
"The fact is, that no tradition has any value beyond man, but a prophecy necessarily, if it is a true one, comes from God. We have no intimation that it was conveyed in any written form, and it was quite possible for the Holy Ghost to have given it again to Jude. I do not at all venture to say that it was so; we really do not know, but we do know, however Jude got it, that it is divine. We know that it is given with absolute certainty, and that it possesses God's authority.
There is a peculiarity when it says, "Enoch also, the seventh from Adam." People have made somewhat of that because they do not understand it. But it is very simple. There was more than one Enoch.
"There was an Enoch before this one - an Enoch the son of Cain. I do not see any ground to imagine something peculiar and mystical in this. At any rate, if there be such, I confess I do not know what it is. But I do know that there is a plain and sufficient sense to distinguish this Enoch, and to explain how he could prophesy. We should not look for prophecy in a son of Cain. But that Enoch taken up to heaven in a most remarkable way - more so, in some respects, than the case of any other man; more so than Elijah, though that was a miracle of similar import and character - that Enoch should be the medium of prophecy we can quite understand, for he walked with God, and was not. It was not that he died, but "he was not," because he was taken up to God; yet before he left the world, he prophesied. We can hardly doubt that he prophesied about the people of his own day. Prophecy always takes its start from what is actually present, and has a hold in the consciences of those then living. The object was to warn of the terrible consequences of evil that was persisted in, and how the evil then appearing would assuredly be judged of God in due time. But the Spirit of God also launches out to the end from the beginning. This is the common character of all prophecy. We find it throughout all the prophets at any rate. I do not, of course, say that it was always the case where the prediction was about something of a merely present nature, but it was so in the cases of those moral pictures which are not bound to any particular time or person. We can quite understand these being made the vehicle for the Spirit of God to look on to the time of judgment when it would not be providential action of the Lord, such as the flood, for instance, but - much more than any acting after that figurative manner - His real personal coming in judgment."
--William Kelly, Jude 1
[end quoting; bold mine]