Star Wars is indeed an original story. It created a distinct fictional galaxy with its own set of rules, conflicts, and mythologies that were new and exciting for viewers and readers.
One of the main themes is the battle between good and evil. The light side, represented by the Jedi, and the dark side, represented by the Sith, are in constant struggle throughout the story. Another theme is heroism. Characters like Luke Skywalker rise to the occasion to save the galaxy. And there's also the theme of destiny, as characters seem to be fated to play certain roles in the grand scheme of the Star Wars universe.
It introduced new planets like Naboo, which was a beautiful and important world. It also showed more about the Jedi Order, like their training methods and hierarchy. And the Clone Wars added a whole new dimension to the universe with different clone trooper types and the various Separatist droid armies.
They've been the foundation for much of the lore. Many subsequent movies, shows, and other media have drawn from the characters and concepts introduced in these novels.
The original Star Wars novels have multiple authors. One such author is Kevin J. Anderson. Each author added their own twist and expansion to the Star Wars lore.