The fair (where this art project partially gets it's inspiration from isn't the American kitsch called Disney Land but the fun fair that has been around in the middle ages and started somewhere around 1133 in Europe. The first steam powered carousel could be found in the 1860's (UK invention) but before that there where horses who walked around and pulled the ride.
When you look at the elephant it looks like a throw back to the elephant that could be seen in another theme park for adults venue, the Moulin Rouge (1889 (they started building the Eiffel tower too that year)). The elephant itself is a non exact replica of a elephant that was made for a theatre production in England but this one can carry 49 packagers for a 45 minute walk.
To credit US theme parks for inspiration of an art project in France is very ignorant. Again great article of a stunning and fun art project.
The capacity for these attractions is not great. I'd have to go back and check my notes (not at home right now!), but one of the two said that the capacity for the elephant ride is just a few hundred people per day. And that the carousel capacity is just a couple hundred people per hour. The rides cost 8 euro each, so that's another way to limit the demand for the rides to what the project can handle.
They really function more as attraction-inspired art installations than pure attractions, as they're not the sort of things that scale well into a high-demand theme park. But they certainly should inspire attraction designers... as attraction design clearly has inspired the creators of these pieces.