Red is the color of arousal. Women use it to attract men. In moments of excitement, the blood rushes to the lips, the cheeks turn pink, and some parts of the body turn red. Women use lipstick, blush to imitate, thereby drawing attention to themselves. Nails are a tribute to this ritual.
Another story: earlier, at the time when a girl's first period began, she painted her nails with a mine, demonstrating readiness for mating.
It is considered classic, since even before our era in China, for example, they rubbed their nails with enamel to get red or pink; in Egypt, the color of nails showed social status; the upper strata of society were indicated by deep shades of red, and the lower ones had the right wear only pale pink tones on nails.
Even before our era, people "painted" their nails red, so it became a classic.