I'll be glad to explain it to you, first of all for your information being a creative player doesn't mean just scoring goals and giving assist.
Grealish last season at Villa scored 6 goals and had 10 assists in 26 games played , does that sound impressive to you ?
His impressive stats last season were others, 3.1 key paases per game (only Kevin had more in the PL 3.2), 70 chances created from open play (only Bruno Fernandes had more 77 but he also played more games than Jack) , 2.88 chances created from open play per game (best in the PL), 83.3% pass success (better than Kevin , Bruno Fernandes and many other players).
He has great accuracy in passing, he can retain possession , he has a great ability to pick up a pass and create a chance, he is intelligent on AND off the ball, he can dribble past players, he can win you set pieces , penalty kicks, he can carry the ball and create chances , get players on him and free up space for his teammates so on.
He can play up front, he can play as a winger , as an attacking midfielder.
Overall he is a Pep kind of player , that js why we paid 100 mil for him and that is why he has started in every game so far.
So you see theres more to football than goals and assists.