Warning: Elements from the book series about the history of Westeros not overtly mentioned in the show are discussed below.
In addition to being a hot piece of Westeros gossip, the identities of Jon Snow’s parents on Game of Thrones is of vital importance to this story. (Or, at least, it better be — otherwise, what the seven hells are we all doing watching this show?) “Winds of Winter” seemed to confirm the famous, book-based R+L=J theory — i.e. Snow is the son of Rhaegar Targaryen and Lyanna Stark — but what does it mean not just for the quest for the Iron Throne, but for the story at large? We viewers/readers know that Westeros has much bigger fish to fry than who gets to sit on that uncomfortable chair.
As vividly experienced in “Hardhome,” ice zombies are coming, and they don’t care which house you’re allied with or which oaths you may or may not have broken. Jon Snow is one of the only show/book protagonists who not only knows of this larger threat, but who takes it very seriously (as he should). I doubt this is a coincidence. In fact, I think Jon was born for this particular fight. Given his own concern with this larger, oncoming war between the White Walkers, his presumed heritage doesn’t just give him a solid claim to the Iron Throne, it may truly solidify him as the main character of this whole, crazy book/TV story franchise. Jon Snow is the song of ice and fire.