Here's why:
* Public image vs. private life: We only see actors' personalities through the characters they play and their public appearances. We don't get to see the full picture of their private lives and personalities.
* Maturity can be complex: Being a "kid at heart" can mean different things to different people. It doesn't necessarily mean someone is immature or childish. It could simply mean that they maintain a sense of wonder, playfulness, and joy in life.
Instead of making assumptions about Leo Howard's personality, it's best to appreciate his talent and the fun he brought to the "Kickin' It" character. Ultimately, his true personality is a matter of personal opinion and speculation.