Well, sh is definitely the archetype of a shell. But I still disagree that it is the norm. After all, I know more people familiar with PowerShell than sh or bash, and I generally prefer rc to either (but I am a 9p gremlin)
Similarly, the BiC ballpoints are archetypal items, like steel wire paperclips or keychains. But that neither makes their design the original one, nor the best. Archetypal items are just the most efficient to manufacture or implement while still being usable. Exactly what sh is