STAR WARS isn't science fiction. Science fiction explores the ways that science can change how humans live... the impact that technology has on human thought and behavior. Had someone written a story in the 1910s talking about a hypothetical 1970s in which there were mass produced horseless carriages everywhere, which not only changed the way we built our cities and homes and office buildings, but which also changed our entire culture's sexual morality, that would have been science fiction, at the time. (Pretty shocking sci fi, too, that probably wouldn't have gotten published.)
A story about people in a future where everyone has learned how to teleport, or where the police are all telepathic, and how that changes the way people live and interact with each other... that's science fiction.
STAR WARS would be science fiction if we ever saw anything like, oh, a political movement to grant droids freedom and equal rights, or if it was established that all of the Senators in the Galactic Republic were from an elite superclass of immortals who had access to life extension technology that they restricted to themselves and their families. Or even if it were revealed that the reason the technology in the STAR WARS universe has been completely static for hundreds of thousands of years is because the insidious Jedi Order has been telepathically stifling original thought in all sentients to 'maintain peace'. Any of that would make STAR WARS sci fi.
But STAR WARS is, essentially, just a fun adventure story where the advanced technology has no real impact on how people live at all. The characters in STAR WARS are us. They are the exact same as us. They have the same kinds of government as we do. They have the same cultural morality as we do. Good and evil in the STAR WARS culture mean the same things as they do in contemporary American culture. The dwellers of 'a long long time ago in a galaxy far far away' are monogamous, apparently primarily heterosexual, marriage is between one man and one woman, etc, etc. Aliens are only alien in appearance; otherwise, they act perfectly human... even gigantic mountains of pulsating slime-slug lust after pretty pretty princesses in gold mesh bikinis.
So, no, STAR WARS is not science fiction. (Neither is STAR TREK, except in very rare episodes like "A Measure Of A Man', where the question of Data's humanity and status as a full citizen of the Federation is explored.)
One of the reasons that true science fiction has such a limited appeal, and that, therefore, most of the 'sf' in movies and on TV isn't actually science fiction, is that true sf explores worlds that are different from ours... generally, worlds with humans in them, but where different technology has caused those humans to evolve difference societies than ours. It requires imagination to enter those worlds, and sadly, imagination has always been in short supply. Always... and never more so than in today's world, where more than ever before, people's active imaginations have been stunted since early childhood onwards by TV, movies, and now, perhaps most pernicious, video games.
If your protagonist is from a world where every woman has 17 husbands, you do not need to reveal right away that it's because the humans there were originally kidnapped by insectile aliens and kept as slaves to the hive, and even after they won their own freedom and killed most of their insect oppressors, they still adapted their society without really thinking about it to match what they'd seen of their one time masters. You can throw this info out in dribs and drabs, as part of your backdrop. And it doesn't need to be central to the storyline at all, it can simply be a form of interesting color in your protagonist's background... he/she really feels that this is the 'correct' and 'right' way to live, because it's all that he/she knows.
Back in the 70s, a guy named Gerry Conway (probably the worst writer and/or editor to ever work in comics, certainly the laziest and most appallingly unoriginal) created a comic series named FIRESTORM. The series was a direct response to Marvel's NOVA, and featured a character who was ripped off from about eighteen different, better sources. Conway also published an editorial in FIRESTORM #1 in which he attempted to head off any and all criticisms of the character's grimly derivative nature by truculently declaring that there were no original characters left in comics, that it was impossible to do an original character.
This is, essentially, the same thing as "every story has already been told". It's an excuse for not thinking, for not being creative, for not bothering to try to do something new. Not every story has been told. Originality is still possible. It's foolish and lazy to claim otherwise... and in science fiction, above and beyond all other genres, it's just silly. Science fiction is about going boldly where no one has gone before. (It's ironic that, as I've already mentioned, STAR TREK is rarely actually science fiction - more often, it's just, as Gene Roddenberry infamously described it in a pitch meeting, "WAGON TRAIN in space".)
I'm not saying writers always have to be original. As I've mentioned before, you will find no bigger fan of pulp fiction than me anywhere, and pulp is never original... it's all hackneyed cliches, well worn stereotypes, oft repeated formulas... tropes and memes that we've all seen a thousand times before. But pulp does this because these tropes and memes work; they remain fun and fresh and exciting no matter how many times they are trotted out, if they are handled correctly. A story doesn't have to be original to be fun. It does have to be written with skill and talent, it has to have interesting characters, it has to take us inside it and make us feel what's going on... but it needn't be something we've never seen before.
STAR WARS is never science fiction, and STAR TREK only rarely is... but STAR WARS is always, and STAR TREK is often, pulp fiction. Sometimes they're even really good pulp fiction.
Nonetheless, science fiction... speculative fiction... is all about newness, innovation, originality.
I love pulp and I love sf. Pulp can never be literature, and cheerfully doesn't try. Science/speculative fiction CAN be literature, it can be great, it can say something important about human behavior and the world we all live in... but it should always, always, always strive to be new and different and unique and explorative.
If you think you're writing sci fi and you genuinely believe that every story has probably already been told and it's not important if you're original or not, you're not writing sci fi. You're writing pulp. There's nothing wrong with pulp... but you should understand the difference.
I just finished rereading Jack Vance's wonderful and brilliant DEMON PRINCES series. Wonderful and brilliant, yes. One of the finest depictions of a human galactic civilization, yes. Science fiction... mrm.... not really. Despite faster than light travel and focused energy weapons, the humans of the Oikumene live exactly the same way as humans of present day Earth, with exactly the same mores, exactly the same cultural taboos... the Demon Princes are evil under exactly the same ethical and moral definitions as shape present day Western culture. There are a few planetary human sub cultures that differ from the norm (the Sarkoy, the Darsh) but they are regarded as vile and noxious by the rest of the Oikumene, and clearly cast as villains in the narrative.
Vance was, I think, far more comfortable writing fantasy than he was writing sf, which is why even his greatest sf is, essentially, fantasy with rocket engines and blasters in it.
There's nothing wrong with 'science fantasy', 'space opera', etc. These are mainstays of pulp fiction, and no one loves pulp fiction more than me. But it's important to use words correctly and to understand what we mean when we say certain things. Science fiction is not simply fiction with advanced technology in it. It is fiction in which some form of technology is central and essential to the storyline, and which examines and analyzes exactly what kind of impact that technology has had and may have on human culture and human behavior.