I've been asked to build a definition page (as if this entire site isn't such an expression), this will be a compressed version (quick read). An argument that appears to exist on it's own is invalid. Tread carefully.
a:dichotomy /dī-kŏt′ə-mē/ - the source and destination, without equal, without other, the division of two (drama) that requires the other for independence.
-a cell division (simple) requires the one, to become two
-biologics (complex) requires two to become one
This (inferred as dual) - the descriptor that requires an empty description, ineffable on it's own. Not to be confused with paradox (imagined + impossible scenario), i.e. a child that "goes back in time" and kills their parent prior to their birth. The is no "back in time", there is only now, that requires a past/future duality.
Lack of true independence - no individual without the other, this includes every experience; of which there is no "outside of". There is no "self made" (see paradox).
The question isn't "how are there some many things if existence is only dual?", the proper (sic) question could be "what is this seemingly individual thing's immediate other".
The "bare bones" of creation, the lowest common denominator that can be examined is two, itself and what it is not. We can extend common examinations, which is, in fact, the act of creation. Building a better telescope to examine the stars. The mind is not directly, the limiting factor, as it is and has always been a creation. (see lack of true independence).
No outside without and inside. There is no "edge of existence", no "creation moment". Everything that can possibly exist already does exist, there is no way to add or remove information (energy), only cycle/recycle.
No true ends, no true beginnings. They cycle rises and falls as is, a human life-span, a dot across eternity (for the sake of envisioning a model of something that could be truly independent).
Always more, to be defined.