Hi there Koshmariel,
Thanks for reaching out to Apple Support Communities. It sounds like you're trying to save edits to Photos but run into an error. We'll be happy to help.
Let's go to, Settings > Photos. Since you're not using iCloud, double check that iCloud Photos is not enabled. Check Cellular Data, and make sure it's enabled if you're using your iPhone away from Wi-Fi.
Make sure you have storage available in: Settings > General > iPhone Storage. If not, this page can help you manage storage: How to check the storage on your iPhone, iPad, and iPod touch. We hope this helps.
Take Care!