For a coaster, it's gonna be Leap The Dips, 1902, oldest coaster still operating.
For parks its gonna be Bakken, oldest park still operating, 1583
For fairs, the Schueberfouer in Luxembourg... 1340!
And for rides, normally carousels are way older than people expect (like say, Disney World just turned 50, but it's carousel is already well over 100!)
Doing a quick check for a flatride.... Blackpool Flying Machine -1904
And for a carousel it seems like Canobie's is from 1898!
Cedar Point’s carousel was built in 1912.
Can borrow this for my answer too.For a coaster, it's gonna be Leap The Dips, 1902, oldest coaster still operating.
For parks its gonna be Bakken, oldest park still operating, 1583