The fact is, Lucas set out to write one screenplay.
It started out, as most scripts do, as a vague plot outline.
It got bigger, and bigger, and bigger without getting anymore refined.
Lucas realised that he was going to have to focus on the most refined part of the plot outline and concentrate on getting that screenplay written.
He has been quoted as saying he envisioned a 12-part saga, a nine-part saga and a six-part saga at various times in the past - the fact of the matter is, in 1976 he had once screenplay and a load of notes.
Notes for a backstory for his screenplay, and notes detailing the more refined tale he had whittled down into the original Star Wars screenplay.
There was no Episode IV, no hint at a serialisation, just work on a film called "Star Wars".
When the film was released there was no Episode IV subtitle, not hint at a serialization, just Star Wars - a condensed version of ALL of the ideas Lucas had touched upon in his early treatments.
It was only after SW became a phenomenon that the "Episode IV: A New Hope" subtitle was added and Lucas got the greenlight to go ahead with his planned sequels.
Whatever was said, and has been said over the years - it is clear that Lucas intended to go back and knock the backstory into shape at some point - otherwise he would not have gone with the "Episode IV" thing.
But that is retty much the start and the end of it, he started in the middle, because that was the part he had written and developed and was interested in making.
He simply left himself the option of going back and making the prequels if he wanted to.
All these "What if"s - what if he'd made Episode I first? What if he'd used a different cast? What if he'd split Star Wars into 18 parts instead of six? etc etc - they are a waste of time becuase.... He didn't.
Star Wars is a phenomenon.
It accounts for six of the top 25 highest grossing movies of all time.
Seriously - it couldn't have been any better.
Just get on with it and enjoy it...
And if you think you could have done it better, then by all means go ahead and prove it.
But don't come back until YOU have six films in the all-time top ten yourself, otherwise you haven't really done any better, have you?
🙂