I think you're right, but for the wrong reasons. Introversion does not mean that people have depression nor are unhealthy. Even if you were to exclude people who suffered from mental illness, the world would still include multitudes of personalities. This isn't to say that introversion and depression aren't correlated or confused for one another. They can share similarities. Some people value alone time, and some people like being in a place where they have more control over the situation.
I lived with a guy who was as healthy as a horse. He was very physically fit, mentally sharp, ate well, and as far I know (we were pretty close) he was not mentally ill. We could watch movies, play games, and do whatever to the wee hours of the morning. We'd go get food and occasionally drinks, shoot ball, and we got into distance running for a while - things tough to get into while suffering depression. . Towards the end of the day, he just needed to crawl back into his cave. We could game together online, but that was the limit to his contact once he was spent.
Introversion is not depression. It's a personality trait.
Bullshit false dichotomy. Introversion has nothing to do with creativity. This is just a passive-aggressive jab towards healthy people that some introverts use to excuse not taking care of their depression.