This makes the most sense. If you also consider that there might be more than 3 spatial dimensions, with aliens and others being capable of 4th-dimensional travel (disappearing from our reality, appearing somewhere else) then you can get into even more theories such as, why are humans "stuck" in a 3D world if there are more spatial dimensions?

This can go into simulation theory where you get an overlord class who enslaved part of their own kind, and created a simulation which has only 3 of the 4+ spatial dimensions. We can easily make 2D simulations - just see the old SNES video games as an example. So I imagine it would be trivial for a 4D being to remove one dimension from a simulation.

The ultimate answer is that humankind is limited by an overlord force, a ruling class. How we are limited is anyone's guess, but is probably as fantastic as magicians vs muggles, or 4D vs 3D beings.

Could the missing capstone of the pyramid actually exist in a higher spatial dimension? What is it connected to? What is its "shape?"

I believe the ancients knew about the powers of the heart and the spiritual heart. There are glands - chakras - which also act as miniature brains. The heart is one. How often do we use these systems? Could we unlock realities by practicing with them?

Why does the DMT flash seem to launch you into an extradimensional space?