In reality, the assembly line had already been around before Ford, but not in quite the same effectiveness as Ford would create.
His real accomplishment was recognizing the potential, breaking it all down into its components only to build it back up again in a more effective and productive combination, therefore to produce an optimum method for the real world.
The major advantages of such a change was that it cut down on the man power necessary for the factory to operate, not to mention that it deskilled the labour itself, cutting down on costs of production.