All things likely fundamentally originate from one thing, which is all of reality itself.

All elements of reality must be contained within whatever is that fundamental source. So digging down into atoms and particles more and more is actually revealing the tiniest slice of reality. If you are observing a single atom, there are many billions being ignored.

To find what reality is, perhaps a search upwards instead of downwards would therefore be better. So instead of looking at tiny particles, look at the totality which us all particles. And not only all particles but phenomelogical elements of reality like what living creatures experience, since those two would originate from and be inside the "all that is".

The fundamental nature of reality must be something which is literally the fundamental being of every single aspect of reality. If something is the fundamental nature of an atom, but not of seeing the color blue, then it isn't the real fundamental nature of everything. As all things would be "made of" it so to speak.

So what is that? Because it's not a quark or seeing a color or an atom etc but the nature of all of these things.