Yes, SUPERIORS is a Scrabble word!

Letter values in Scrabble US: S 1, U 1, P 3, E 1, R 1, I 1, O 1, R 1, S 1.

Is it a valid word?

SUPERIORS is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

one of greater rank or station or quality
the head of a religious community
a combatant who is able to defeat rivals
the largest freshwater lake in the world; the deepest of the Great Lakes
a town in northwest Wisconsin on Lake Superior across from Duluth
a character or symbol set or printed or written above and immediately to one side of another character

Also: higher-up, lake superior.