Bob Dylan - “Knocking on Heaven’s Door” (Pat Garrett and Bill the Kid OST, 1973)
This song is so easy to play even I was able to figure it out (now that I know a few chords). Trying to get my daughter to learn it too. She resisted until I showed her that Avril Lavigne did a version. But I overheard her singing it to herself this morning, so it looks like the earworm has taken hold!