Kobold Avenger
Legend
All Celestials except for Quesars (which are constructs) come from souls, for Fiends some come from souls and some are spontaneously created from the Lower Planes themselves. 2e often had the idea that Good was a hard thing to do or be, but Evil was easy and this reflects that idea.Or the stories and beliefs could just be wrong. I find the idea that the lower planes are so vastly more power than the upper planes just insulting. Definitely not my vision of the multiverse.
But perhaps the most important idea outside anything in the Planescape setting, and also something that is probably 2e but could have carried over in later editions: is the idea that if the Celestials were powerful enough to vanquish all Fiends, why would there ever be a need for any Heroes like the Player Characters?