Google is going downhill, the day I finished my internship I sweared I'll never in my life work on any money-making, no-challenge project. A bunch of engineers do enjoy what they do, they work on the cool projects, that's enough to keep it going; the rest is just cattle, work for the cash, enjoy the free food and the reputation of working at Google; I'm still sick of being bombarded with the "changing the world" nonsense.
Change projects/company, find a mentor and/or a mentee, build new stuff; find your purpose, unleash your intellect. Don't fall for the "changing the world" lie.