I'm not sure I have any groundbreaking thoughts on the topic (pun sadly intended), but I like a lot of the thoughts in this post because I think it's so much more important to cater to the way the story is told rather than the originality/lack of originality in terms of set-up or setting. That stuff is all dressing to the characters and storyline, which as you say can be a quite hard sell if it strays too far from audience expectations.
Even low-concept stories can be "less original" than certain high-concept stories depending on the way they deal with the "human element" of it all, especially the main characters. John Wick, the first one, is a plot so simple you can sum it up in "Keanu Reeves kills a bunch of people to avenge his dog," but thanks to the extremely interesting cast of characters in a fleshed-out setting, it never feels stale even for a moment. Then on the other side of things, explaining the premise of Weathering With You takes a paragraph at minimum, but at its heart it's a romance story about two broken teens running from themselves, and it never really veers away from the expected despite the extremely complicated and original premise. Both of these are movies I love, but not because/despite of how "groundbreaking" they might be; it's just because they tell stories with very good emotion and purpose.
I even have this dichotomy with my own stories, I think. Hands Held in the Snow is a romance story with such a clear set-up that you can guess half the story beats by looking at the protagonists. But, at least I hope, the characters and aesthetics are strong enough that they keep people reading and enjoying it all the way to the end. Its setting is a vaguely clockpunk Venice-like city and has all sorts of details that set it far apart from most fantasy worlds, but I've never marketed any of that for a moment because I know that'd get in the way of the characters, which are the only part that matters anyway.
Then, my story ATL is a retrofuturistic sci-fi detective series about a nonbinary, superpowered slacker who goes around solving crimes and getting caught up in comedic antics, where each story arc is explicitly divided up like manga volumes despite being prose. It's a VERY tough sell because there is no story quite like it, and for a while I used that uniqueness as the main appeal. It didn't really work, and now reflecting on this I actually see why. The off-beat mysteries and the extremely vocal protagonist are the parts readers most often laud the story for, and I should probably focus my energies almost entirely on that. Or something? I'm not good at the marketing part for stories quite yet...
And my next story, a secret project that will be releasing extremely soon, has such a low-concept premise that the entire project basically has to be marketed on the title alone (and it's a real good one thankfully). To have this story succeed, I'll basically have to "trick" readers into reading it and getting invested in the characters/jokes before the Weird Stuff finally kicks in, otherwise they'll probably get bored and quit reading after chapter 2. For this project I will have to HIDE the originality somewhat. (Though since it's not out yet, we'll have to see how that actually ends up working or not.)
Honestly originality is sometimes a big barrier, especially when it comes to fantasy/sci-fi. Getting audiences interested in a story DESPITE the hurdles of having to learn this new world's "rules" is one of the main things that are required by any given story to succeed. Anything from Star Wars to Mortal Engines to Scott Pilgrim all have interesting worlds that really make their stories work, but they only work because the characters and not-especially-"original" stories power them through it.
Maybe these thoughts are too jumbled but I will post them anyway lol