Mac Photos originals

I find the originals from a finder window where I click on the photo library and then "show package contents" and "originals".

And don't do that. There are no user-accessible parts of the photo library in the Finder. You should only access them from the Photos Window.

Want to back up your originals? Export them: File -> Export -> Unmodified Originals.

With the current Photos the best method to store originals outside of the library is to export the unmodified original using the option to group them by Moment, i.e. location and time and name them with one of these naming options:

The originals will be exported to folders names for the Moment, i.e. date and location.

Every few months, I export the originals (as described by Yer_Man) taken since the last time, and then use Exiftool (there are probably others) to sort them automatically into folders by date. (You can export directly into date based folders, but I find the structure doesn't suit me)

These are then backed up to my network drive.

This is in addition to backing up my library both to time machine, and to an external drive.

Hello MischiefManager,

Be careful modifying any Photo Library content using finder.

System Photo Library overview for Photos on Mac - Apple Support

“WARNING: To avoid accidentally deleting or corrupting a Photos library, do not alter the contents of a library in the Finder.”

Since you have an external drive using Time Machine could make this all much easier for you. Back up the library in Photos on Mac - Apple Support

That being said, I am wondering if you accidentally moved the originals rather than copying them. This can cause them to be excluded during a backup. Change where your files are stored in Photos on Mac - Apple Support

You might be able to have the library reorganized by repairing it. Repair your library in Photos on Mac - Apple Support

I hope this helps.