Yes, HUMANITIES is a Scrabble word!

Letter values in Scrabble US: H 4, U 1, M 3, A 1, N 1, I 1, T 1, I 1, E 1, S 1.

Is it a valid word?

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

studies intended to provide general knowledge and intellectual skills (rather than occupational or professional skills)
the quality of being humane
the quality of being human
all of the living human inhabitants of the earth

Also: humanistic discipline, liberal arts, human race, human beings.