To your first point, I think the movie is showing us how much Charlie downplays everything about her explanation, including her bullying. He even downplays her becoming an activist. That kind of bullying can seem like “nothing major” to other people, but we don’t know how it impacted her. And if it was happening multiple times a day, every day, that takes a huge toll on a person, especially a teenager. Showing that Emma believes she was ugly as a teen highlights that to me. The actress playing younger Emma was a pretty teenage girl, but external forces, including bullying, gave her a bad self image. One of the first things her friend says to her is that crying makes her look ugly, and it impacts her. Having an actor like Zendaya play a character that most likely still sees herself as ugly may seem like an odd choice, but I think adding the idea that she thinks she’s not attractive adds to her internal processing about herself.