Sometimes things that should happen fairly just don’t, I have no idea if you are good enough for the role, but if you are it could unfortunately be as simple as she has got her feet under the table and charmed them.
Let me tell you about an interview I had for a teaching assistant job, probably 15 years ago now, I had a degree and was working in a supermarket, which I went back to and never tried again after my confidence took such a huge blow.
I travelled by train, I got to my destination very early, earlier than I needed, but didn’t want to run the risk of being late. Walking out the station I saw a pigeon get killed by a car, that was a bad omen. I walked around the local area to kill time, it was cold so eventually went to wait in the school, signed in. Suddenly a door opened and one of the interviewers looked at me and and in a despairing tone said “well we may as well see you NOW, as your so early and here before who SHOULD be next!”.
The interview went horribly as I was completely off stride and couldn’t manage to say anything right, nothing I’d rehearsed would come out. The interview I think was cut short. When I went to sign out, there was a handsome guy who was meant to go in when I had done, he was flirting away with the receptionist, who was hanging on his every word, I meekly asked if I could sign out, the receptionist clearly irritated, pushed the book over without breaking eye contact with this guy, off I went absolutely crushed.
I know this is different to your problem OP, but what I’m saying is, I knew I could have done a really good job in that position, but nothing went right, I didn’t make the right noises, or charm anyone and I sure as hell wasn’t liked by anyone there, someone has to be the loser in any given situation. Somehow she has made herself noticed and liked to your superiors, it’s not fair, you should have been considered, but not everything is in your control all the time.
You could think that actually at least you can do your job and she will have all the worry that goes with a higher role, or you can go find another position, where they will notice you, see your worth and like you, if that’s what you want and are able to find that.