I used to go through a similar thing when I started composing music...I could do melody & harmony and a basic beat, but all the stuff in between, that makes a song feel "full" and gives it weight and a certain energy...I couldn't figure out how to do it. I wasn't even sure what to ask, not that I had anyone to ask...
So eventually I just gave up. Instead of continuing to attempt songs where I would only end up getting stuck, I decided to stay where I was comfortable: with 8-bit music. Sure, maybe it was simple and not "real" music, but I actually understood it and I could make it sound good. I had fun~
Fast forward a year and a half later: I've started making serious attempts to return to more detailed, contemporary sound, and to my surprise it's gotten easier. A few weeks ago, in a major triumph, I made my first rock accompaniment that actually sounded...normal. ^^; Like an actual song, and not just 'drums + various dissonant guitar noises'. This was something I'd been thinking I would simply NEVER be able to do, mere days before I just...did it.
All that is to say that, sometimes accepting your limits, with any art form, can be the best thing for you. At worst, it means you'll be "stuck" doing what you're best at and what you can enjoy without hassle. And at best, it means you'll be slowly and subtly learning as you go (as I was~), and the next time you decide to attempt that impossible task, you'll surprise yourself with your newfound skill.
If you have trouble with writing full narratives, there's nothing wrong with just having fun making characters and settings and premises. That's basically all I do on my DeviantArt account: it's the one space I have where I can just create * things * without any expectations or strings attached. If I draw a random OC, or come up with a random story idea, I can just put it out there and let it go. If I have more ideas about it later that I can build on, great. If not, that's fine too. Really, a lot of artists do this; the epic storytellers aren't as common as you might think from being here all the time. ^^;
Y'know that saying, 'if you judge a fish by its ability to climb a tree, it'll live its whole life believing it's stupid'? I think that might apply here. There are lots of valid ways to be creative and tell stories, and the fact that you're struggling with one of them and always needing help doesn't mean there's something wrong with you. Maybe it just means that's not the one you're best suited for, and you'd have more fun if you found a medium/style that actually played to your strengths.
I'm thinking of all the things I've considered doing for the many stories that I simply don't have time to make into comics/novels...there's the usual 'limited series of concept artwork with descriptions', but you could also do one-shot-ish comics simply showing cool events that you just want to draw, without bothering with all the buildup of a 'proper' story. If a random, completely unexplained thing looks cool enough, people will still like it and take interest in it. Maybe it can't survive on a comics website like this one, but you could certainly find success on other platforms.
If you're more into lore exploration, you could even try something like RWBY's World of Remnant mini-series, where you just talk mysteriously about how the world works. ^^ I've seen things like that both in comic and video form...again, it might not do well on Tapas, but in other places, definitely. Webtoons, even, is no stranger to comics that are just info+cool visuals.
I think I need to bring this rant to a stopping point...in conclusion, you don't have to quit what you're trying to do; if it's what you really want, despite the struggle, you should definitely keep trying. But if you DO decide to quit, that doesn't mean you have to give up on the story you want to tell. You can always find another way.