No, I don't think the character existed in any true sense outside of the mythological one. What nails it for me (pun accidental but pleasing) is the combination of: zero contemporary non-scriptural references, scriptural failure to mention known historical events, scriptural references which are anachronistic to the political and cultural era in which they are supposed to have occurred, and so on. The claims of magic and the sheer mountain range of blatant lies that have been deemed necessary - and useful - to prop up the story of the character's basic existence are merely the cherry on top.
At the age of five, Skagra decided emphatically that God did not exist. This revelation tends to make most people in the universe who have it react in one of two ways - with relief or with despair. Only Skagra responded to it by thinking, 'Wait a second. That means there's a situation vacant.'
