You find Chen stormstout when helping the tauren, orcs and trolls set up orgrimmar. So he was there from the beginning. As far as I remember he was the only panda.
He doused people in alcohol, set them on fire and split into 3 separate pandas. All abilities that made it to monk in Wow.
IMO, anyone who dismissed the story in mop as too “kiddy/disney” both didn’t actually read the story but just hit skip and probably thought illidan/arthas/sylvanas were “literally me”