This feels like a really stupid question but I genuinely don't know. Gliders existed before powered airplanes, right? So people would probably could have made paper airplanes for fun prior to the Wright Brothers, but I have no idea and just had this as a weird shower thought and was curious about it now.
afaik yeah, they're like a thousand years old at least.
There's lots of examples in nature of things like those helicopter seed pods.
There are a lot of technologies where we've kind of known they would work for hundreds or thousands of years, but we were lacking some critical piece - usually high quality metal or rubber or ball beargins or something, to make it actually happen.