Scrooge is a miser. He is very stingy with his money and hates spending it, especially on things like Christmas celebrations or helping the poor. He is also cold - hearted, often being rude to people like his clerk Bob Cratchit.
One of the main themes is redemption. Scrooge is a miserly and cold - hearted man at the start, but through the visitations in the story, he has the chance to redeem himself. Another theme is the importance of kindness and generosity, which Scrooge learns to embrace. Also, there's the theme of the past, present and future influencing a person's present actions and future destiny.
Scrooge was chosen maybe because of his extreme greed and lack of kindness. His transformation could have a big impact and serve as a powerful example.