Yes it is. That's why it's aimed at children. It's as deep as it gets; it's the foundation. The most basic, basal conceptualizations of what it means to be a good person. Bravery, honesty, compassion, discipline. The bare minimum requirements of a human being, from which all right action stems. Just because it's simple doesn't mean it's shallow. And if you think adults don't need a refresher, look at the world around you.
There's a psychological concept called Dunbar's number, posited by Aynsley Robin Dunbar, which makes the obvious and self-explanatory assertion that there is a limit to the number of people you can maintain relationships with, and seeks to estimate that limit. It's estimated to be anywhere from 100 to 250 people, but the number isn't the important part; the important part is that in studying this, evidence has emerged that fictional characters count towards the limit. Which implies that our minds don't make a meaningful distinction between our understanding of real people and fictional people. This is important because there exists mountains of evidence across many many contexts to suggest that the people we surround ourselves with shape our own self perceptions and behaviors. If you surround yourself with people who lie, cheat, and steal; who hide from challenges and consequences; who ignore people in need and dehumanize people with opposing views; who excuse themselves from commitment, you will end up just like them. But if you expose yourself to people who are brave, honest, compassionate and disciplined, you will become more brave, honest, compassionate and disciplined, and resist the slow descent into complacency. And as we see from Dunbar's number, those people don't need to be present in your life or even real.
That's why people keep reading the Bible past Sunday School, and that's why people read and watch capeshit and westerns and war movies and hardboiled detective stories and sword-and-sorcery and all the pre-postmodern tales of heroism that Reddit wants you to scoff at. That's why we have those stories in the first place. That's why we bother telling them. These are not things you learn once and never again. We are hardwired to conform to the world that surrounds us, and the darker that world gets, the more we need a light.