I mean, I'm an extrovert and I have to massively disagree to the majority of people's opinions on this.
There's a misconception that introverted = nerdy, shy and creative, and that extroverted = charismatic, happy and neurotypical. This is kind of ridiculous and a lot of people who have mental illnesses just dismiss their experiences as "introverted" when they're not introverts - they're depressed extroverts.
In reality introverted = self-sufficient and home-bodied, and extroverted = friend-focused and conversational. Both are equally interesting and equally likely to go through a variety of things.
I'm a massive extrovert myself and my protagonists are, too. Jason's character arc is actually focussed on the fact he is and doesn't know it. Right at the start of the story he makes himself out to be self-sufficient and to not be afraid of anything but over the course of the story he goes through hardships and learns to confide in and rely on others. He learns to accept being extroverted and making friends doesn't make him boring or weak, as he previously thought. Similarly Foreas likes to think he can be fine with loneliness as long as he throws himself into his work. He constantly says he's just "doing his job" but over time has to learn to accept that he needs to have connections with others to be happy. He goes through a lot of denial about being in love with Jason because he has convinced himself his work is his life and he doesn't need anyone else. He also has to meet his estranged sister again and she helps him remember what love and collaboration can feel like.
I've got other characters that are introverted, like the third main character Annabelle who creates a whole fake identity so that she can run away fro her past. She doesn't connect with others very often and is happier with a small circle that she can trust. In fact, she spends quite a long time travelling alone and being emotionally distant from others. She only ever becomes truly symbiotic with one person - her so-far unnamed love interest "J". She actually doesn't see "J" for a long time either - they are reunited after a very lengthy separation. The two of them like to maintain few friends and are very home-bodied. They don't feel the desire to gather people together and go on wild adventures like Foreas and Jason do. They like to have time where they can be alone and recharge.
The point is, both introverts and extroverts can be protagonists, but it depends on what you want them to behave like. If you want your character to be outgoing and to collaborate with other people you're gonna want an extrovert. If you want a character to be less of a team player and to be more self-sufficient then go for an introvert.
Neither is better or worse for the role... And also a lot of people don't know what the two terms mean lol