Special relativity came first, and it was actually to solve paradoxes relating to fast-moving magnets. Maxwell’s equations produce a fixed speed of light, which breaks Galilean relativity, but they have Lorentz symmetry baked in. Just gluing them on to Newtonian mechanics can cause problems.
His solution was to work out a weird, different but observationally equivalent mechanics that would work. Decades later, it was realised matter is waves which internally move at the speed of light as well, so it’s not that weird after all.
Special relativity came first, and it was actually to solve paradoxes relating to fast-moving magnets. Maxwell’s equations produce a fixed speed of light, which breaks Galilean relativity, but they have Lorentz symmetry baked in. Just gluing them on to Newtonian mechanics can cause problems.
His solution was to work out a weird, different but observationally equivalent mechanics that would work. Decades later, it was realised matter is waves which internally move at the speed of light as well, so it’s not that weird after all.