Well, I don’t know for sure, but I will tell you what I believe.
After the flood G-d showed Noah a rainbow and told him that every time he (or us) sees a rainbow to be reminded that it is a reminder of G-d’s promise that He will never destroy the earth again via rain. So no matter how bad the storms get or how bad it floods or how hard the meteorologist tries to scare you; after the rain the rainbow is a reminder of G-d’s promise.
So the colorful rainbow is our reminder in the sky as we are G-d’s reminder on earth. G-d not only created a colorful rainbow in the sky He created us to be colorful on earth as a reminder of His promise. When we look up we get a colorful beautiful view of G-d’s reminder and when G-d looks down He gets a colorful beautiful reminder on earth.
Again no matter how bad the rain gets a rainbow is a reminder of the promise. No matter how bad we get our variety of skin color is G-d’s reminder of His promise. So basically we are G-d’s rainbow.
So with that said; no matter what skin color you have, you are just like a rainbow; a beautiful sight to see.