>>3 My take on it, its was probably like this:
Imagine a spirit in high-level mental plane.
All his needs resolved, he has only creative drive and curiosity to explore.
He casually creates tulpas, wonderlands and 'mind-palaces' being
something like a tulpamancer with energy equivalent of atomic bomb per microsecond(higher planes - high energy).
One day he decides to take this a step further and gives his
wonderland a really huge jolt of energy to see how it evolves,
and it explodes and expands absorbing this energy, but due being
artificial, unable to produce its own(entropy) it gets colder
and more boring, so he sends his tulpas inside to spice it up.
As the wonderland gets larger and colder it gets less energetical and more
material, with tulpas aquiring denser etheric bodies and creating
their own sub-tulpas(repeatedly).
These tulpas become local spirits/gods/demons/etc, who eventually devolve down
towards material incarnation as their corruption and density increase,
becoming their own subjects and eventually giving rise to
intelligent monkeys who start wondering how it all began.
tl;dr its a demiurge's dream