As an early Macintosh tool, ResEdit's UI was intuitive enough for non-programmers to pick it up and apply superficial changes to the images, sounds, UI layouts, strings and level save files of the Mac apps of their time.
Nowadays I can't even swap out the icon file of a Mac app without it running aground on the notarization stuff in modern versions of the OS. The age of ResEdit is as dead as a dogcow.