There's an episode where they find a huge underwater pyramid that has ancient Greek writing on it. A character gets possessed and starts speaking Greek. It turns out it's The Temple of Minerva built by Neptune. Now if you had a thing for mythology, like I did, as a kid you probably notice those are the Roman names of the gods. And Minerva is a black woman. This is in the early 90s.
This "replacement rot" has been going on for a long time
That is an interesting question. I wonder if an anthropologist would have any thoughts about that?
I'm going to make a wild guess that is because we call the planets using roman names so the association becomes Jupiter:planet Zeus:god but Hercules/Herakles is a person so lacks that confusion.