Superhuman and 'Superman'

The most common contemporary use of the term 'Superman' has little to do with Nietzsche's.  While the former refers to physical characteristics, the latter signifies a psychological self-overcoming: of Ressentiment, via the affirmation of Eternal Recurrence.  Nor does it have any relation to a Darwinian Superhuman being.  For, even though the latter does connote a projected possible physiological condition, it is one that is the product of a mutation of Human characteristics.  In sharp contrast, in the fiction, there is no biological connection between the inhabitants of Krypton and the Human species.  In other words, he might be a male, but there is no 'man' in Clark Kent's alter ego.  So, the common use of the term 'Superman' is far removed from the concept of the surpassing of the Human species that either is explicitly proposed by Nietzsche, or is implicit in Darwinism.