Based upon a need to have a library of base materials time was spent searching for real world examples. Each material is named and comprises of a Principled BSDF (and in some cases a Refraction shader.
The materials can be used as is or altered to fit you personal needs.

There are no textures involved in the materials as they are just basic colors.

Each material has a unique name rather than "material-002" or such name.

The materials contain several examples of metals, vehicle paints, popular cartoon character colors, fruit, human elements, and fluids. (More to be added as a free updates)

The included RGB Blender file contains 130  168color materials

Changelog:
23/08/2022
UPGRADE has 168 total materials
Added 38 more material colors
Some materials now have textures
Check out Gummies, Car Paint, Jelly... These materials have multi color selection.