I'm a Loser was considered for release as a single until a track was written that featured the first uses of what in populer music?
I'm a Loser:  Written by John Lennon, (though credited to Lennon–McCartney), it was considered for release as a single until Lennon wrote "I Feel Fine". I Feel Fine:  The song has one of the first uses of guitar feedback in popular music.
guitar feedback