They are types but not dogmatic descriptions of individuals. Each individual can be more or less categorized as having both 'types'. Jung thought that we needed both qualities in balance. Being too introverted is an over identification with the internal innate potential.
Extraversion is an over identification with the environment.
MJ Further reading Jolande Jacobi, The Psychology of C.G. Jung . Johnstone, Margaret MJ Bloomsbury Guide to Human Thought 2. Creativity And Play Bloomsbury Guide to Human Thought 3. Extraversion Bloomsbury Guide to Human Thought 4. Jungian Thought Bloomsbury Guide to Human Thought 5.