I saw Star Wars with a friend in Grand Junction, Colorado in June 1977. We sat through 3 showings in a row. In those days if you just sat in the back between showings, this theatre wouldn’t kick you out. By the third showing I almost had memorized the scenes and dialogue word-for-word.

For sure in that showing, the human Jabba scene was included. People can say whatever they like, but I know it was there. I recall seeing Return of the Jedi in 1983 being surprised Jabba changing from a fat human to a big slug, but thinking oh well Lucas can change whatever he wants.

The only thing I can explain this is they were in a hurry to release and left it in the first theatre prints. Then when those wore out, all print distributions after that omitted it. I have read elsewhere that they did change many audio effects during the first run between May 77 and July 78. It wouldn’t surprise me if that scene got quietly cut early in the run.