I'm guessing it ended on ch28 because if you're not regurgitating the same old garbage to the isekai gobblers your fantasy manga gets canned nowadays.
This is not really that tropey, at least it's not running your usual isekai tropes, but there is a few others from the shoujo genre. It is an adventure shoujo with a reverse harem. It doesn't have game mechanics or a japanese teenager being reborn or scantily clad women. The MC isn't super OP and we've seen her work hard to become strong (most of it offscreen though), her motivations are selfish but she can't bring herself to do the wrong thing for her own gain. She's competent but isn't written to be smarter than everyone else, and for a reverse harem manga it has very little fanservice to the point you can barely notice it.
I agree it could have been fleshed more, but it ended at ch28 so clearly they weren't given the time to do so.