Have you read “Case Closed” by Gerald Posner? If not, you should.
I personally believe that Castro was behind the JFK assassination. Maybe as simple as telling Oswald that he wished he would do it. There is also a chance that the mob did it but Castro is the obvious choice.
I do agree that Oswald took the action by himself. The Cubans/Communists could have simply told him to buy a scoped high powered rifle and left it up to LHO to do the rest.
No way for me to prove it of course, just my belief.