Disclaimer: I have not read many Superman Comics.

In the Superman Movies and in the TV Show Smallville, Superman's iconic S was used as The El family crest.

Was this original intention?

I originally thought that the name "Superman" garnered the S.

Then if you listen to the old Superman radio show, it was a boy who gave him the name "Superman" based off of the S he was wearing.

So this ends up as big "chicken in the egg" question:
Which came first, the "S" or the Superman?