no one in this went on to big careers

Keith Gordon had a successful acting career and is a very successful director.
Scheider went on to have a great acting career.
One of the teenagers Billy Van Zandt became a big time screenwriter and producer and directed some
Your post is ignorant

What about the shark? He got 2 sequels after this one

John Williams went on to be best Film Composer in the Universe...collecting 5 Oscars...

Mike became a marine biologist.