I’d never realized it was this easy to rename multiple files and directories in Emacs dired!

When in dired, type C-x C-q to make the buffer writeable. The modeline will change to “Editable” and you are in wdired-mode (Writeable Dired). Edit filenames like in any normal Emacs buffer, including commands like query-replace. When done, type C-c C-c to commit the changes to disk! There are more advanced options (editing permissions etc) when needed.