Who invented nail polish and when? What was it made of?

Mixtures that can be applied to the fingernails and which then remain in place after drying to produce a colorful impact have been around since at l;east as long ago as 3,000 BCE. The name of the exact individual who first attempted it, and/or the first to be successful, is lost in the mists of time.

Nail polish originated in China and dates back to 3000 BCE. Around 600 BCE, during the Zhou dynasty, the royal house preferred the colors gold and silver. However, red and black eventually replaced these metallic colors as royal favorites. During the Ming dynasty, nail polish was often made from a mixture that included beeswax, egg whites, gelatin, vegetable dyes, and gum arabic.

https://en.wikipedia.org/wiki/Nail_polish

Here's some more detail about developments over time, including the modern liquids.

https://www.byrdie.com/history-of-nail-polish