Son of Man refers to the original man, or Anthropos, that first appeared in early Near Eastern myth. So that a synonym for Son of Man according to the archetypal interpretation might be ‘primal Man’ — Man spelled with a capital M.
Edinger explicates the archetypal reading of ‘Son of Man’ as equivalent to the Anthropos or Divine Man — a primordial, capital-M figure from Near Eastern myth rather than a merely historical person.
, Transformation of the God-Image: An Elucidation of Jung’s Answer to Job, 1992thesis