It doesn't 'need' the nouns, we just have them. Using them seems sophisticated, also I guess it would not be surprising to find the nouns on cans of paint :)
red = czerwony / czerwień
green = zielony / zieleń
black = czarny / czerń
white = biały / biel
Surprisingly, I think there are nouns for all basic colours, but not for the basic concept of 'blue'.
- blue = niebieski / ?????
But for its most basic shades, there are nouns:
dark blue = granatowy / granat
light blue = błękitny / błękit
This is funny as "granat" would be more a dark red in german.
Blue is a very special color. Many languages didn't have a concept of blue. They had a word for the color of the sky, of the ocean, or of cornflowers but not general blue. This was "invented" by the germanic people. At least one good thing they brought to the countries they invaded. g
Many names of colors are in fact male adjectives.
The masculine form is treated as the "default"; this is the form that is listed in dictionaries. In paper dictionaries you won't find feminine or neuter forms, because they want to save space. In electronic ones those forms are included in inflection tables under masculine entry.