The more I think about the inclusion of the cover of The Middle by Kelty Grey in Supergirl the more I think it was a good choice in that scene.
When I first saw the movie I thought that it was a bit jarring, but I actually think that the contrast between the texture of the song and the grittiness of the fight scene represents the duality of Kara's character very effectively. Filmmaking is a medium that has both sound and visuals (as opposed to comics which is just a visual medium), and so sound can be used to tell the audience something that the visuals are not. Basically, a song or voice over shouldn't be used to repeat what the visuals are already saying. (E.g. Bring Me To Life in Daredevil)
I've heard people saying that they wished the original version of the song was used instead, but I think I prefer the cover they used because it highlights an undercurrent of Kara's character that is only beginning to appear at the very end of the movie. She's this character that has spent so much time angsting, and her arc is about rediscovering hope and learning how to be her own kind of hero. Using the original would represent an earlier version of Kara, whereas the cover better showcases where she is emotionally in that moment.
Anyway I really liked Supergirl and I think it deserves more love!
