Re: "the so-called Population III stars"
It was called just "Star Wars" - all the contemporary posters called it that, the magazine articles, TV reviews etc. The UK ones as well as the US imports and "from our Hollywood correspondent".
The on-screen text crawl at the beginning described it, as it still does, as "Episode IV", titled "A New Hope", before giving what is basically a "previously on the mind of Mr Lucas" recap of the story so far. Which gave it the feel of one of the old serialised story shows and the sense that there was a great big galaxy we were about to jump into.
From interviews and articles at the time, Star Wars was meant to stand alone as a single film, with a happy ending (except for Chewie being left out of the medals).
Then it all became a tad more successful than anyone really expected, definitely more than the studio did, and a sequel came about. But still without a clear plan - Leia kissing Luke was just a bit cheeky at that point (and for those of us who'd read the officially-sanctioned tie-in novel "Splinter of the Mind's Eye" surprisingly restrained - had they gone off each other?) - other than that there were going to be two sequels. So we get an unresolved story, far more than just a simple sequel hook.
By the time "Return of the Jedi" came out - and you could go to an all-day triple play, still starting with just plain old "Star Wars", Lucasian interviews were including the "I think of it as three trilogies" blurb and the comment that Vader and Kenobi had last met in a fight on a volcano (which I recall at the time was taken with a pinch of salt, another call back to the worst excesses of the old swashbuckling fantasy stories, fisticuffs on the crater's edge).
Even for the 20th Anniversary CGI-fest special edition releases, the posters still called the first film just "Star Wars". It was only with the release of the prequels, 1999 onwards, that the retcon rot really started to set in and saying "Episode IV" or "A New Hope" was heard outside of the pretentious set: "Phantom Menace" was very explicitly referred to as "Episode I" on the posters and advertising.
Next week:
In episode eleven of "When Nerds Collide" we will be explaining away the discrepancies in the Y-wing fighter/bombers; good night.