When Lebron James puts up just one season of 28/10/7 shooting 50/40/90 from the floor, then we might be able to have this conversation. Bird put up similar numbers multiple times.
Bird also made the players around him better, wasn't afraid to shoot the ball, and could score at any time from beyond the arc, inside the arc, and with his back to the basket, or even in the paint, from any area of the court.
Lebron is a fantastic basketball player, but he is a product of the ESPN hype machine. He cannot score from anywhere on the court, and he doesn't have that killer instinct that Bird and Jordan had, or Kobe and Pierce, for that matter.
Lebron is unstoppable at what he does best. But that doesn't make him remotely comparable than a Bird or Jordan.