Jude presents us with a 'problem.' He explicitly sites 1 Enoch in Jude 14 plus he has numerous allusions to traditions about the Old Testament that are not found explicitly in the Old Testament. What weight should we afford these texts and traditions? As I argued in the previous post on OT quotes in the NT, if a tradition is used that is an element of the Jewish worldview of the author and isn't an explicitly Christian worldview (e.g., how Jude sees Cain as the archetype of a false teacher leading others into sin), then we're not bound to investing those Jewish traditions with Scriptural authority. The text of Jude still has full Scriptural authority and its point is fully valid, we are not required to understand, e.g., Cain as the archetype of a false teacher leading others into sin. We simply need to see Jude's point. Jude is using an example that would be familiar to his audience, nothing more, nothing less.
This type of approach doesn't solve all of our problems fully, though. Jude cites 1 Enoch in a manner showing that he believes it to be inspired and authoritative. What do we make of that? 1 Enoch is not in our Bibles. Some, in the early church, argued for the inclusion of 1 Enoch in the cannon because of Jude's citation of it. Conversely, some argued that Jude should not be in the cannon because it cites 1 Enoch. God did see to it that Jude was included in the cannon and thus I believe we are bound to seeing 1 Enoch as inspired. That does not mean, though, that 1 Enoch should be canonical. Many things that are inspired are not canonical. I certainly believe the Apsotle's Creed is inspired, as I believe Amazing Grace is (the Chris Tomlin rendition too!). As being inspired by God, it does carry a certain amount of weight and authority. However, it does not mean that it is authoritative to the same degree that Scripture is.