I was doing mock interviews with trainees today, all of whim have interviews tomorrow, Friday and Monday.
They really want the jobs; they would be good at those jobs. They need to be as good as they possibly can be at interview because the people interviewing them don't know them like I do. Competition round here is fierce currently (too few vacancies for too many ECTs) and I am going to do my absolute best to give them every advantage I can.
So, although we were on Zoom, I picked them up on slumping, not smiling, not making eye-contact, fiddling with hair or face, saying 'kids', starting every answer with 'Soooo' or 'Er', saying 'we' rather than 'I', or using 'like' as a punctuation mark, a well as talking too fast or too monotone.
Many of these are stress symptoms but unless you are aware of them, you can't consciously overcome them. But they can all be overcome.
We practised until they made eye-contact, consciously slowed down, sounded enthusiastic when talking about enthusiasm, eliminated 'like" unless used as a comparator or example, etc.
It is personal, OP, but at interview you are essentially setting yourself up for sale. You are saying, 'Choose me!' and you need to show your best side to stand out against the other candidates. We have to assume that, like you, they will bring strong performance on placements, wonderful references, good research into the school and great answers to the interview questions. The interviewers might end up with three they could appoint. How you would fit into their staff team then comes into play - and confidence, coherence, likeability all contribute to that final decision.
A mock interview is a grwat place to get honest feedback. Obviously ask for feedback after real interviews too, but it is rarely as detailed and often too 'kind', but you need to take what you have been told, be grateful, and try to act on it.