Knowing certain people doesn't make him a mob member. He knew far more Dallas police officers than he did mobsters. That doesn't make him a police officer either.
Ruby was not a mobster. He was not a member of any criminal organization. He was not right in the head.
Do you realize that when the Warren Commission interviewed him he believed that Jews were being killed in the jail basement? That he denied being part of any conspiracy, but was worried that people would take their anger out on the Jews because he was jewish?
Look at the details of the Oswald shooting. There is a trail of movements. There is no way Ruby could have planned it in advance. Read up on it.
The movement of Oswald was well known - the press was there in force. I'm sure you've seen replays of the television coverage. Remember, Oswald had made several previous appearances at the Municipal Building, including attending at least one press conference. With Ruby's ties to the cops and local reporters, he likely would have had good intelligence as to when Oswald was being moved.