“System“ is using about 5GB. What is included in this category?

See info...How to check the storage on your iPhone, iPad, and iPod touch - Apple Support

About storage on your device and in iCloud - Apple Support

You may have some corruption since other is high consider reinstalling iOS

Restore your iPhone, iPad, or iPod to factory settings - Apple Support

Hi fyip,

Congratulations on reaching 8,000+ points and making it to level 6! 🙂

We have started a virtual party in your honour over in the level 6+ lounge. This link should get you there once the bouncers have been handed your name by the management. Look forward to seeing you there soon.

tt2