Songs that have stood the test of time.

Hava Nagila  by unknown, but sang and played by whole bunch of artists and all together too.
Money For Nothing... sang by whole bunch of R&R singers and musicians at a time in famous video.

Hava Nagila of course. (We are, after all, talking about songs that have stood the test of time.) I have no idea what that song is about but I have danced to it many, many times. It's a mitzvah!?!

Dylan's "Like a Rolling Stone" is a great song and covered by many. But his "All Along The Watchtower"is more personal and subversive. Hendrix covered it best but there are many others....

Well if we're going to include songs like Hava Nagila, then I will have to bring up Happy Birthday. 
Happy Birthday has been covered many, many times. 

If the test here is that the song invites reinterpretation, I'll nominate two from Todd Rundgren.  I love both songs and both reward a great voice:

Pretending to Care
Love is the Answer


Both have been covered to great effect many times - but Love still awaits the definitive interpretation IMO.