Don't get hung up on Star Wars. The cinema industry accelerated between the World Wars. In that period, many genres developed. By the mid seventies, George Lucas wanted to create a space adventure to utilize the new blue/green screen technology for special effects. His first choice was to do Flash Gordon, a story from the thirties with established domains and characters. But Lucas couldn't get the license to Flash Gordon, perhaps because its owners were very protective after a pornographic parody film in 1974 called "Flesh Gordon." So Lucas had to quickly start from scratch, with a story line that was only partially developed. He did not even make Darth Vader the father of Luke and Leia until the second film, Empire Strikes Back.
By the mid seventies, World War II was 40 years old, more than halfway back to the massive introduction of cinema. So, while Star Wars was a turning point for special effects, its story line was a very old-style good-guy, bad-guy battle.