FWIW, I agree with you and am in the same boat. I joined a FAANG so that I could work alongside and learn from truly impressive people. So far, after a few years of working at my FAANG, I have not worked alongside one single person who I would consider impressive. I won't go so far as to say they're "low IQ" or dumb or anything like that. I enjoy them as people and I like working with them, but they certainly don't inspire me and I do not feel like I am learning things from them that further my career. All of them, even the ones at higher levels than me, seem just as clueless and lost as I am. And that's an awful environment to be in.
It's frustrating, disappointing, feels like you were lied to, etc. My only advice to you is to just quit. Don't stick around searching for something that you already know isn't here. It's very unlikely to get better.