Boy am I impressed that you signed up just to ask a folk music question. And you mentioned Bob Dylan.
[sub]It’s not a tear, I just got some dust in my eye, that’s all. [/sub]
There are many phrases that make their way into lots of folk songs (e.g., rubber tired buggy, rubber tired hack, two went to the graveyard but only one came back). There are many reasons for this. Most repetition is due to the origins of the songs themselves. Many folk songs were written on the spot by songsters who knew many other songs. It is likely that they borrowed phrases.
Many songs were written as they were performed (e.g., barn dance songs). Let’s say that a group is playing a 5 verse song and everybody is dancing like they’re being ridden by witches. Of course, the group does not want to stop so they make up more verses. It’s easy to borrow from other songs.
Many folk songs (especially those of Appalachian origin) are derivitaves of Child ballads or Broadside ballads. This, too, explains revisited lyrics.
As to the actual significance of the Jack of diamonds (as opposed to the five of clubs)… I’ll have to get back to you. However, some cards do have significance… Queen of Spades (forgot why), and the Deadman’s Hand (forgot which cards, but it has something to do with Wild Bill Hickock [or some other dude] holding those cards in a poker game when he was shot.[sup]1[/sup]
[sup]1[/sup] I’m sure fellow dopers will provide correct information here; them be’s smart.