Using the old adage that the triumphant get to write history any way they please, I'm more surprised that the Romans didn't claim to invent polytheism, rather than the Greeks. I mean, to the victor go the spoils, right? And the Christians worked damn hard to erase all mention of other deities from history and replace significant secular events with their own. Except where Rome was concerned, which they held high as a Christian victory over the "heathens". And remember: 4 out of 5 Roman lions agree, Christians just taste better.