I'm a bit resigned that my aim is not where the markets might be
You never know. The markets change all the time. Contrary to what agents and publishing houses would have you believe, they have no clue what the next trend will be. They're guessing most of the time.
Keep trying. And make sure your writing is the best it can possibly be. If you have a good story to tell (and you can write well) people will read your novel.
No one ever assured me I had any literary or artistic ability anyway. I've always told good stories, but that's not enough.
Success is what you make of it. If you define success as a writer by setting your goal to be like Stephen King or JK Rowling, then that's quite a mountain you have to climb.
If, on the other hand, you simply want o write the best book you can possibly write, then you will succeed.
If you have good stories to tell, but feel your "literary" ability isn't up to par, then you know what you need to work on. If you have the means, take some writing classes - community colleges are cheap, by the way.
If you don't have the means, scour the boards on here and elsewhere looking for someone who can help you develop your skills. Someone with a degree in English would be the best bet.
So, no, success is never guaranteed. But successful people get there by overcoming the odds.