I highly recommend the book "Quiet" by Susan Cain. It explores the trait of introversion in depth and makes many thought-provoking commentary about our cultural preference for extroversion. The poster can probably be described as an "ambivert".
At the end of the day, none of these terminologies matter... These labels are just "models" of how we see ourselves. I agree with the sentiment that premature self-labeling is dangerous. Because they tend to become self-fulfilling prophecies. (e.g. I'm not good at math, I'm a nerd, I'm good at hockey, I'm INTJ, I'm an introvert).
At the end of the day, none of these terminologies matter... These labels are just "models" of how we see ourselves. I agree with the sentiment that premature self-labeling is dangerous. Because they tend to become self-fulfilling prophecies. (e.g. I'm not good at math, I'm a nerd, I'm good at hockey, I'm INTJ, I'm an introvert).