Yes, NAIVEST is a Scrabble word!

Letter values in Scrabble US: N 1, A 1, I 1, V 4, E 1, S 1, T 1.

Is it a valid word?

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

marked by or showing unaffected simplicity and lack of guile or worldly experience
of or created by one without formal training; simple or naive in style
inexperienced
lacking information or instruction
not initiated; deficient in relevant experience