How Do I Clean Up a Messy Photo Library?
A sensible order of operations when a library has grown out of control.
Start by gathering everything into one place. Photos scattered across phones, drives and downloads folders cannot be sorted or deduplicated while they are in six places.
Fix the dates next, because everything downstream depends on them. Then let the dates do the organising, into folders and filenames. Only after that is it worth hunting duplicates, since duplicates are much easier to spot when files are named consistently.
Takeout JSON Metadata Fixer covers the middle steps: dates in, then renaming and foldering by those dates, with screenshots and documents separated out if you want. Free for your first 500 photos.