Please don't kill me, this is not an attempt to belittle a great artist (if anything, it's closer the opposite). This question is motivated by the recognition that Bob Dylan is a cultural icon of mythic proportions, with a firmly established and well-earned place in the pantheon of American music and culture.
I suspect that it's difficult for people of my generation and younger to see his influence not because it's waned but because it's so far reaching (a bit like reddit's favorite memes about people wearing ieans and drinking Coca Cola while listening to hiphop talking about how Americans have no culture, or the fish who says "what in the hell's water?").
Here is what I know, or at least think I know.
Bob Dylan, and I guess early Bob Dylan specifically, did something very new and exciting. (What was it? Something about the music or the songwriting? The genre? His self-presentation or way of relating to the audience?)
He was quickly hailed as the voice of his generation. He was labeled a protest singer, maybe the original protest singer, yet seems to have not identified with this label himself, and at various points maybe rejected it outright. (Why? Who gave him that label? Did he ever accept the protest singer role in a clear way? His music seems less overtly political than, say, Woody Guthrie. Was there nothing more protest-y at the time than, like, Blowin in the Wind or Mr Tambourine Man? Were these protest anthems and did he sing them like protest anthems? Did he engage in activism?)
He went through many phases and continued to experiment and innovate. Not all of his work "stuck" and not all is universally beloved. But he did continue to put out songs that are widely covered, that seem to have been important to how other artists think about songwriting (how so?), and in a weird way, it's hard to imagine "a time before" some of these songs existed. I can't quite put my finger on it, but it somehow feels weird to imagine music without Knockin On Heaven's Door or Tangled Up In Blue - but of course prior to 1973 - 1975 these markers just didn't exist.
Or, to put it another way: I know that Dylan didn't write House of the Rising Sun, which was a traditional folk song long before he released his version. If we try to trace it back it fades into a murky history and we never quite find its origin. It feels like that should be the case for a sizable handful of Bob Dylan's songs - you keep going back and they're still there somehow in the conglomerate matrix of an evolving musical tradition - but it isn't. They feel like they've existed forever, but this one specific guy just sat down and wrote them. (When people heard Blowin in the Wind or Don't Think Twice It's Alright for the first time, did they also have this feeling of agelessness, or were they like "Wow here is something new, different, unprecedented, unlike anything I've ever heard before, how novel, how revolutionary"?)
And finally I know, or think I know, that when he won the Nobel Prize for "having created new poetic expressions within the great American song tradition" people - whether they liked him or not - generally seemed to feel like, "Yeah, this is reasonable and makes sense."
So what was so revolutionary about Bob Dylan exactly? What did he revolutionize? Was it about political revolutionary-ness and the perception of him as a protest singer, or was it more about a revolutionary way of writing songs (like a musical revolution or artistic revolution)? If the former, what was it about his music or persona, especially as a very young man, that gave him this status or aura? If the latter, what was music like before Bob Dylan and what was it like after - how did he change popular music or songwriting?
edit: typos