It's interesting that Elvis "I Can't Help Falling In Love With You" is sung at a football match.
The song is taken from "Plaisir Amour" by Martini, a classic art song.

Many traditional folk singers have been characterized as "dreadful singers". To hear Pete Seeger at his best, I recommend his first album for Folkways, "Darling Corey". Pete ruined
his voice in later years and it had to do with throwing his head back while singing which constricts the vocal cords. That method of singing was probably derived from Woody Guthrie who was a short man and had to look up when he shared the mic. It was a habit that many folkies got into. Also, Pete belting out "Wimoweh" didn't help.

One would be hard put to call Louis Armstrong a great "singer" but few could do what he did with a lyric or a song. I would guess that "dreadful singer" might be in the ear of the beholder.

The same song with different versions, called by the folk musicologists as "variants" might well be part of a definition of a folk song.