Play through Mount Hyjal again sometime then. At their shrines are NPCs that detail how each of the ones that died gave their lives to save Azeroth.
And as destructive as the Horde have been to Teldrassil and Darkshore, the Horde is not actually a world ending threat. Given, Cenarius should have been a general at the Darkshore Warfront, but other Wild Gods were likely busy with the Azerite mcguffin matters, as we saw with Aviana.