Yes, SHALLOWER is a Scrabble word!

Letter values in Scrabble US: S 1, H 4, A 1, L 1, L 1, O 1, W 4, E 1, R 1.

Is it a valid word?

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

lacking physical depth; having little spatial extension downward or inward from an outer surface or backward or outward from a center
not deep or strong; not affecting one deeply
lacking depth of intellect or knowledge; concerned only with what is obvious