We're not the largest in absolute output, but we are literally the best manufacturer in the world, and we are the 2nd largest.
We manufacture lots of stuff, often the most state of the art and difficult things to manufacture. We're very good at it.
And we've sat around close to full employment for so long, the only way to convert more of the economy to manufacturing is to either import workers, cannibalize other sectors of the economy, or automate even more.
Yes, a larger share of the economy is services, but is there some objective optimal ratio of services to manufacturing we should be shooting for? If so, what is it? No one ever says.