What Does The Song Mean?
There is quite a lot of history wrapped up in this one sad song, and while not all of it may matter to the story Game of Thrones is telling in season 8 - after all, the Ghost of High Hart and her prophecies aren't in the TV show - the inclusion of "Jenny of Oldstones" still feels intentional. On the surface level, it's a song about love and loss, which makes it a prime choice for those awaiting a battle which many of them may not survive. Like earlier songs featured on Game of Thrones, "The Rains of Castamere" or "The Bear and the Maiden Fair", "Jenny of Oldstones" is surely also a song which most in Westeros are familiar with and may even find comfort in on the eve of battle. (And of course, audiences may also find Podrick's singing of it similar to a scene of another song being sung before battle in the film, The Return of the King.)
On a more symbolic level, however, "Jenny of Oldstones" comes directly before the scene in where Jon reveals to Daenerys the truth about his lineage - that he is actually Aegon Targaryen, the son of her brother, Rhaegar and Lyanna Stark, and therefor the true heir to the Iron Throne. Relaying this news to Daenerys is a big step for Jon, and she reacts as many could have guessed (which is to say rightfully suspicious even if we, the audience, know it's the truth), but Jon has yet to give any indication of how he plans to act on it. Predictably, this scene between them is cut short by the arrival of the White Walkers, which means it's very likely Game of Thrones won't reveal what Jon decides to do about being the rightful heir until after the Battle of Winterfell. But the inclusion of "Jenny of Oldstones" may offer a clue.
Prince Duncan gave up his crown to marry Jenny, the woman he loved, which may hint that Jon could very well choose to do the same for the woman he loves. It'd be a controversial choice, to be sure, but it's in line with the sort of person Jon is - someone who has never sought that kind of power for himself and a man who keeps his promises. Jon has already given up one crown for Daenerys, what's to stop him from doing it again? Plus, he not only loves Daenerys, he swore an oath of fealty to her and it's possible that even this bombshell won't make him break it.
Then again, the strong ties between "Jenny of Oldstones" and Jon's father, Rhaegar as well the Prince That Was Promised prophecy could be a hint of Jon fulfilling some grand destiny. Whether that means sitting the Iron Throne, or being the promised prince who brings the dawn by slaying the Night King - or even both! - remains to be seen. But this old, sad song comes with a lot a meaning, and it's only being sung at this moment on Game of Thrones for a reason.
Game of Thrones season 8 continues next Sunday, April 28 at 9:00pm on HBO.