Sounds like D&D to me. Its just Alerons version. He has upper planes and lower planes same as D&D. Angels in D&D are celestial beings that live across the upper planes. We know that at least one celestial race lives on the material plane of the Land. That is one race of sapients and one perhaps sapient tree. That’s not saying your wrong. Aleron definitely has his own twist of the higher and lower planes. I wish Ricther would increase the power of his Portal system in order to reach other planes. Then Aleron would be forced to define the planes of existance along with there inhabitants.