Periodic reminder that "introvert" is not a synonym for "shy" or "bad at public speaking." We can talk to random strangers, we can speak to large audiences. It just exhausts us.
One of the best explanations for it that I've heard -- albeit immensely simplified -- is that introverts and extroverts both have batteries. Introverts recharge on our own or in low-key social situations without a lot of people. Extroverts recharge in higher-end social situations, big groups, and vibing with a crowd. And some of us also have smaller batteries than others in the first place, so we need to recharge more frequently.