Sharon Gallagher

I have an iPhone 5SE with 16 GB that worked well for me until I installed iOS 15. I am a 70+ year old grandmother who only uses the phone for messaging family, email, taking pictures, but primarily for listening to podcasts. Since the update, the storage message says iOS uses 7.04GB, and the System Data uses 4.58 GB, rendering my phone pretty much useless. Is there anything I can do to remedy this problem besides buy another phone? Can I uninstall iOS15?