I agree that white is usually more associated with positive and black with negative things. However this has nothing to do with racism. This symbolism is wide spread (and likely linked to psychological factors that actually unite us like the day/night associations) Case in point: some tradional african art uses the same symbolism, where black represents power, evil and death and white is linked to the concept of purity, light and hope (https://pangeasculptures.com/african-art-the-symbolism-of-colour/).
When I think of color science, black is defined as an absence of color while white is defined as the presence of all colors. In computer science, the equivalent RGB values for black are 0, 0, 0 and for white 255, 255, 255. In other words an absence of color is black and the presence of all colors is white.
Colors in paints are made with pigments, in other words, they rely on the natural ability of materials to either absorb or reflect light. A material that absorbs all light is black, and a material that diffusely reflects all light is white. White pigment, for example, Ti02 (titanium dioxide) Black - carbon.