Bavarian pilot Captain Joe quite merrily described why airlines paint the nose cones of their planes black. It turns out, that “radome” is where the weather radar is kept. A black rubber cover was used to protect that dome and the equipment inside from debris abrasion. The rubber cover was only short-lived, as the airlines then turned to much less expensive black paint.
Later, airlines stepped away from the rubber coating and then painted the noses with black paint. Back then, the fuselage was covered in lead-based paint to prevent corrosion but wasn’t allowed to be sprayed over the nose due to the metal compounds of that paint. So yet again cheaper black paint was applied without interfering or limiting the Radar’s performance.
I more modern times, airlines have stepped away from the color black and have implemented colors more in line with their logos.
Eventually, that colour range grew more and more, and airlines painted their planes in their colour of choice to match the livery!