The main themes include the power of childhood. In 'It', the children have a certain innocence and courage that allows them to confront the evil 'It'. There's also the theme of the cycle of violence. 'It' represents a kind of never - ending cycle of horror that the town has been trapped in for generations. And the theme of facing one's inner demons, as the characters are forced to deal with their personal fears.
Well, in Stephen King's 'It' novel, a significant theme is the battle between good and evil. The kids are the representatives of good, trying to defeat the ultimate evil 'It'. Then there is the theme of loss. Many characters in the story have lost loved ones or parts of themselves due to 'It'. And the theme of growing up. The experiences with 'It' are part of their journey from childhood to adulthood.
One of the main themes is fear. The fear of the unknown, as the entity 'It' takes various forms that are often very terrifying and unpredictable. Another theme is friendship. The group of kids in the story form a strong bond as they face 'It' together. Also, there is the theme of memory. The characters are haunted by their past experiences with 'It' throughout their lives.