I've never read anywhere if Paul Simon's I Am A Rock was specifically a response to John Donne's No Man Is An Island, but you couldn't blame a jury for ruling that way.
Exhibit Number One: John Donne's assertion that you're not the only clam in the chowder and that when you walk through a storm you can hold your head up high because you'll never walk alone.
No man is an island,
Entire of itself,
Every man is a piece of the continent
A part of the main.
If a clod be washed away by the sea,
Europe is the less.
As well as if a promontory were.
As well as if a manor of thy friend's
Or of thine own were.
Any man's death diminishes me,
Because I am involved in mankind,
And therefore never send to know for whom the bell tolls;
It tolls for thee.
Exhibit Number Two: Paul Simon's declaration of the opposite.
However...it's lines like "If I never loved, I never would have cried" that make me think Simon is not so much saying he's separate from the world as he is wishing he had been. He strongly proclaims, "I am a rock. I AM an island," but it's got a bit of the old "methinks he protesteth too much" about it.
What starts as a declaration of independence ends up being a realization that independence isn't all it's cracked up to be. Like the following panels from Bill Watterson's Calvin & Hobbes:
Truth is...we need each other, even though sometimes it hurts.