That doesn't matter too much. He certainly had the intent to build the story beyond the first movie, and, putting aside these external circumstances and focusing on the movie itself, the 1st movie does not form a coherent complete narrative yet, in isolation it barely works.

Compare it with other film trilogies: clearly SW OT is more similar to LOTR and Matrix than to Godfather and Jurassic Park. In the latter cases it makes sense to speak of the original, not so much in the former.