@pleonasm - You could argue that there aren't any real original dances. I mean, a lot of the group dances of the 50's have their origins in the group dances of a hundred years ago or more. They used to dance like that in Jane Austen's time.
Even the more provocative dances are similar to what people would do in poor communities back in the day, or in other countries, or even in the wealthier western countries during some eras.
There's nothing new under the sun, it's all just recombinations and renaming the same old moves.
After all, there are only so many ways a human can move their body. There's nothing wrong with that.
But, if there is a documented time when someone said "this is The Twist" then we have to take that time as the origin of that dance, otherwise we'd be looking back forever, trying to find the original.