King Creativity's name was not Romulus, but instead, either Numitor or Amulius
Roman, as a name, derives from the Roman Empire, The City of Rome, and being a Roman Citizen. Rome comes specifically from the story of Romulus and Remus
Romulus and Remus were twin brothers who were also princes who were also demigod children of Mars, the god of war. When it came time to pick the name of their kingdom, they got into a fight, and Romulus killed Remus, winning and naming it after himself.
King Creativity being Romulus only has any connection to Roman, and also says that Remus is dead and buried in the Aventine Hill.
King Creativity's name would not be Mars because Mars is a War God, and has no connection to Creative Endeavors, so going further up the family tree:
Romulus and Remus' brother was Rhea Silvia.
Rhea Silvia's Dad was Numitor. He was supposed to ascend to the throne, but was overthrown by his brother, Amulius.
I think Numitor makes sense as a name because he's supposed to be One Creativity, but was split by something out of his control, as well as being the Grandfather of Romulus and Remus. Also, the added bonus of there being no -an, -on, or -us ending, having no connection to either the light or the dark sides.
Amulius is equally cool for lore purposes, as he was both Good and Bad. A good king but used sly tactics to reach them. I like the -us ending, which implies that he leans further toward the dark side than the light side of the mindscape, and gives Patton more of a "reason" to cause the Creativity Split: He wants a "good" form of Creativity
This. Is peak.
I think this is a peak headcanon. I don't have a specific one for King Creativity in my head. I just use whatever is most convenient. But this is certified peak.