I think the confusion lies in the difference between what, in our world, is
exoteric vs
esoteric religion. Or rather, religion vs. mysticism.
The esoteric (mystical) traditions generally see that there is "the One" and then an array of beings between humanity and the One. The Abrahamic traditions call these angels, with some very detailed hierarchies (e.g. Dionysius the Areopagite). In Hinduism you have devas, asuras, rakshasas, etc, similarly in Buddhism.
Rudolf Steiner's anthroposophy, which draws from Western esotericism and follows the structure of Dionysius's hierarchy, says that angels are actually evolving beings, that the first level above humans (angels proper) were at a human level on a previous Earth, just as the second level (archangels) were at a human level two previous eons ago, and were at the angelic level when angels were at the human level.
Meaning, Steiner takes an evolutionary perspective on all beings, and that the "gods" were once at a human level. This doesn't apply to the Absolute or One. Funnily enough, this resonates somewhat with the MCU take, in which we could see the Asgardians being at a higher evolutionary level than humans.
The exoteric view varies by religion, and it seems that D&D, by and large, takes this approach, but adds its own cosmology on top of it, which in some sense muddies the waters (and I think what
@doctorbadwolf is taking issue with). Ultimately D&D is about playability, but I do hope that any future planes product emphasizes the "build your own cosmology" approach. Or maybe that's simply a product that I need to write

.