Lol! Not Anaximander or Anaxagoras?...Reading the conversation between you and daliwali is quite enjoyable. I generally agree that "noumena" are irreducible in expression (e.g.: GΓΆdel's incompleteness theorems), but can be experienced (i.e.: that's what "gnosis" is). These "archetypal forms" are the foundation of the "Prisca Theologia"/"Primordial Tradition"/"Perennial Philosophy"/etc.
In other words, they are what all individual expressions hold in common and reasoning can point to them. One of the clearest descriptions of how humans connect to this process that I've seen is from Miriam Joseph's Trivium. I would type it out here, but the quote won't fit, so I'll post it with some extra notes on its own temporary webpage: https://letslearntogether.neocities.org/bookclub/quote01
why does existence of a noumenal world hinge on belief? i believe that noumena exist but is also not knowable... the human mind does not deal with that ambiguity and uncertainty well.