Basically "the speed of light" should be called "the speed of massless things" or possibly "the speed of causality" or something. We just call it "the speed of light" because light is the first thing we discovered that travels at this special speed.
*the star is because everything about quantum-chromodynamics is terrible so gluons don't really ever exist as particles themselves. If they did they would travel at the speed of light.
* not actually infinite, because reality itself propagates at a finite speed
(I’d love to know if this is wrong - this is my best attempt to make sense of it from college classes)
Not a physicist, but I've often wondered if the basis of QFT got off on the wrong foot by making time a privileged coordinate instead of a quantum operator like it does for position.
Speaking of which, time(-of-arrival) measurements in quantum mechanics have recently attracted quite some interest: The classic Copenhagen formalism doesn't seem to give an answer here (or at least not a unique one – it depends on how you perform the calculation). Meanwhile, Bohmian mechanics does seem to make a precise prediction. It will be interesting to see what experiments will yield.
Given that "light" is fundamentally a electromagnetic wave and its propagation in spacetime is constant, and this results in time slowing down when you go faster to maintain this property, it isn't unreasonable to hypothesize a more fundamental basis here.
Personally, I think adding in the time component will be essential to completing this puzzle but all in all it makes for an avenue of investigation which is interesting.