If you're looking for things that are completely unique to cycling, you're going to be pretty limited. Cycling clothing borrows from other areas (like golf, with the notion of a turbulent boundary layer.) Suspension innovation spills over from Moto-X (which doesn't specifically cover droppers, but they're an extension of that.) Frame materials are trickle down from NASA (as is so many other things.) And (as already mentioned) tubeless tires were already a thing. The idea of liquid latex as a sealant may have come from cycling mostly because it solved a problem that didn't exist with motor vehicle tires - thinner sidewalls were more susceptible to puncture and smaller volume means higher pressure, so the liquid latex is an elegant solution. So that might be one. I don't think clipless pedals came from anywhere else, but someone can keep me honest on that one.
Overall, if you want to look for something that is very much unique to cycling, you might have to look for something that solved a uniquely "cycling" problem. For example, changes to frame shapes over time to address cycling-specific applications. A great example of this in road bikes is the differences in frame shape for different applications - like look at the way seat stays come into the seat tube on most aero road bikes now compared to just 10 years ago. In the past, they met the seat tube near the seat clamp, but testing showed the bike is more aero if they come in lower. Geometry differences like that might be the most bike-specific innovations over the years. In less performance-related arenas, saddles are a big one. Saddles shapes and materials have changed a lot over the years, with some fairly radical comfort implications. But personally, I think one of the biggest innovations that seems to be cycling specific would have to be electronic shifting. Ironic that a long-time SSer would say that, no? But I've been riding my gravel and my road bike a lot lately, the former having e-tap. And it is a world of difference in terms of reliable shifting and smoothness. It may just be something you don't miss until you experience it, but having stumbled into it, I can't believe how big a difference it makes.
