Q: drag and drop thumbnails to order them and then to rename them

In a user album you can drag to create a custom order

You can not manually order system albums

You can not change file names (any change like that must be done prior to import ad no changes can be made to the content or structure of the photos library manually)

YOu can assign a title to a photo in Photos

You probably need to read the Photos help file and overview and maybe take a class - Photos is a totally different Paradigm  where you manage photos virtually using a SQLite database - you do not manage the files at all

LN

Do you want to batch change the titles of the photos below the thumbnails or the filenames of the imported original files?

• To rename the original files with a prefix and a running number, you can only rename them by exporting and reimporting.  The export panel "File > Export > Export ... photos" will rename the selected photos according to the file name preset you select. Select "Sequential" to add a running number.
• If you want to batch change the titles in Photos, the options in Photos are limited. You can select all photos at once and assign a new title to all of them by entering the title into the Info panel title field. To add a running number, use an Apple Script. We posted a few scripts for batch changing in the User Tip section (Photos for Mac).
• For example:
  • To change the title to the filename: Script: Batch Changing the Titles to the Filename w/Extension
  • Batch Change Title to Text w/Padded Sequential No.
  • Batch Change Title to Capture Date-Description-Padded Sequential Number

And we are back to hidden posts.  Worse than ever. Your post - 12 hours old - did not show until I posted. I hope yesterdays maintenance did not cause this.