Ultimately no one on here can say as we don’t know who else applied and how they compared to you. The webpage says they interview around 69% of applicants, so while that is higher than some courses, a good number of people don’t get to interview stage, not necessarily because they are bad applicants but because they are squeezed out by stronger ones. As the poster above says, to get a place you have to be in the top 36% (which is the actual statistic from the admissions page, not 47%) not of a random group but out of the field of very able and well qualified candidates who are passionate about this subject.
I can’t give any real suggestions but I notice you don’t mention your GCSEs - could they make you less competitive than other candidates? Especially when viewed in context of your school?
Also, the score your written work got for A level course work isn’t really relevant to how highly it was rated by Oxford tutors. A level marking is largely about ticking the right boxes to get the right number of points. If you look on the Oxford course website they list the criteria they are assessing written work by which are much more holistic. Again, that’s not to say that your written work wasn’t excellent (maybe it was) but I don’t think you can extrapolate just because it got a certain mark at school that it must be strong enough (in the field if all applicants) to get you an interview. Most people applying will be getting top marks on their school work and Oxford is looking for more than that.
You can request feedback but won’t get it till after this admissions cycle has finished. I am sorry you are feeling worthless. There are lots of other amazing unis out there and with such great predictions you still have great options.