I'm in a similar boat. I found that concentrating on short stories was really helpful to build my confidence in my prose. I am currently bouncing between two novel ideas, with maybe 15k words on one, and about 10k on the other. I ended up not liking my first attempt (the longer) and plan to go back to the table and do world building again before making another attempt. On the second, I am slowly writing it out, but it is painstaking work.
While I haven't solved this problem, I think what you and I need to do is the same: just keep writing. Don't edit as you go. The more you build it out, the more you'll feel connected to your characters, and the more you'll want to explore them in other situations. Get your ideas on the page, and eventually you'll be able to figure out what you specifically don't like. And then you can start again or start a new project with that in mind.
Wishing you the best!