I bought this cropped pants and a gray jacket in case I have a job interview or something. This suit is gray color with white stripes on it. I do not know whether I suppose to wear black heel shoes, black flat shoes, or maybe another shoes. I am clueless because I do not dress on a regular basis. Is it not black shoes to assume corresponding to each color?

Yes mostly black can with any color. Try some black flat shoes you can not really go wrong with any of the choices that you gave.
A gray suit set is definitely a neutral example, you can use with any color. I would definitely avoid open toe shoes, which are not suitable for a job interview. As a general rule heel shoes are great for a job interview, but do not go too high, it makes not look professional. On the same note flat shoes may look a little bit casual. But you can play with colors to make you feel like a star at the office as rich saturated colors, especially in the jewel tones like emerald green, ruby red, cobalt blue, royal purple, they will look chic and flatter all skin tones. So there would be a red camisole under your suit with a red pumps heel shoes. Just not too low cut at the camisole, or you could do on a button up.

Because it will be for a job interview, black shoes are your best choice. It does indeed can go with each color and gives a polished and professional appearance. Maybe I would go to the pointed shoes with a kitten heel shoes because they look smarter