Superman was an alien being and his race of aliens were all murdered and he was the only one left from his race of aliens and had superpowers which he kept finding out about his powers accidentally. He was a goody two shoes and did try to protect humans from his villains. Jesus was born from rape and helped people, he wanted the rich to pay their shit and not take advantage of the poor. If they were to switch, Superman would have survived and Jesus would have still been killed. Jesus would have been raised in some farm and hate people who are not like them. He would be trying to get them to love other people and wouldn't want the rich to take advantage of the poor. He would be kicked out by his adoptive parents and would be homeless. Like he was in the story from the byble. A Kyle Rittenhouse type would have shot him and he wouldn't be seen as a martyr. Superman had his demons but the goody two shoes in him, he would have obliterated the Romans and survive persecution. It might be a worse religion if it was Superman!

Factitious? or Fictional?

The latter is a modern retelling of the former, which was itself based on messiah myths popular in the bronze age.
The star babe, comes to earth, can fly, tries to put the chosen people back in their place as rightful rulers of the world, dies and comes back and then promises to return when most needed, but doesn't.
Both versions were written by Jews who never got paid for their work.

Well, before there was a Clark Kent, there was a Hawaiian Superman, the demi-god Maui! As sung to us by Braddah Iz (Israel Kamakawiwo'ole)