"If most of my speculation is correct, then despite the stark difference between tales of the supernatural and deities, don't they essentially share the same origin?"
"So, is it possible for tales of the supernatural to gradually become true deities by building Shrines, absorbing faith, adopting Divine Remains Bones, and through a series of complex and orderly enhancement measures?"
"Taking it a step further, those 'inferior spirit energies,' those 'fundamental spiritual matter,' could very likely be related to faith. And as a human, not naturally possessing these things, that's why I need the Shikigami's Shrine, to provide me with an extremely small supply of faith in advance, so that afterwards I can follow the normal process of becoming a god..."
It all connects! Everything is connected!