I think this provides a good way of beginning to grapple with it. If the planes are our perception of the cosmos, or, for basically all of us, our potential future perceptions - given that we haven't developed on all of them, but our potential is latent here. Even when we do fully develop, we are, as the Norse may say, still in Midgard. There's a vast realm of non-human things (each with their own plane perceptions), which is the supernatural. That's the whole rest of the cosmos and probably the Unmanifest too. Then there's the really small stuff, the sub-natural, although that doesn't quite explain it either. Almost all modern physics insists that looking at really small things will explain the big things, then wonders why it doesn't. Looking at big things doesn't explain the small things.

If occult teachings are right, the big things are more powerful and important than the little things (so Einstein, Maxwell, Newton and others win over the quantum physicists), but the little things still exist, but won't be consistent across space and time. That does make some sense.

Ultimately this stuff is utterly alien to humans. It's why we struggle, I struggle, to map it to our reality Lovecraft was right, there's tentacles out there.