Applied at primary school for teaching assistant

I started volunteering at a primary school earlier this year in February, hoping to gain experience for teaching assistant roles. I initially volunteered on Tuesdays and Thursdays, but I enjoyed it so much that I added Fridays and participated in school events whenever needed. After four months, a paid teaching assistant position opened up, and I was excited to apply. I felt I did well in the interview, despite being anxious. The head of the school called me later that day to say I had interviewed amazingly and that I had made a positive impact on the school. However, they decided to hire a parent who had been volunteering, citing their 'more experience.' I was told I would be kept in mind for future openings. Fast forward to the end of term, when another teaching assistant resigned. I kept checking the school's website for new job postings but was confused when I found out that a new position had opened up and was filled without any notice to me. It feels disheartening because I dedicated so much time and effort, and while I appreciate the positive feedback, it seems like actions speak louder than words. I really thought my commitment would lead to a job opportunity, but it hasn't. I'm feeling quite frustrated and emotional about the whole situation.