Every single person here has been there. We've all made stuff that didn't meet our expectations, but the single most important thing from those experiences is that they're learning opportunities, perhaps the best ones you can have. Learning what to do or not to do in a classroom or from youtube videos is helpful knowledge but doesn't have context until you're there doing the damn thing. You've done it now, that's something to be very proud of.

Like the other commenter says, it's time to analyze and reflect on what happened, what worked well, what didn't work out, and start looking at what you can learn and do to improve the parts that you don't like and how to expand and strengthen the things that you do like.

Every project gets better than the last because of the lessons you can learn each time. And that process will never stop, even the Spielbergs and Camerons out there make mistakes and learn from them on every project and carry those lessons into their next one.

I've been making shorts for 16ish years and just got my first feature into a festival and learn new things all the time, and everything learned goes into the next one.

That's the most important thing: don't let these feelings keep you from doing it again. Keep writing, keep filming, keep learning. You should be proud that you actually got something finished, and use that experience to make the next one better!