● Good Will Triumph: The first meaning you probably took from The Grinch when you were a kid was that good will triumph over evil. Simple. As a kid, it was obvious that the Grinch was the villain. He's a mean one. He wants to ruin everything for everyone. He's not even nice to his dog! And he tries to ruin everyone's Christmas. But he fails because Christmas is such a powerful force that it melts his evil heart and he actually returns everything he stole. For a child, this is a simple and reassuring message. It is what we want to believe about the universe and, at Christmas, all things are possible.
But if you think about it, there is something strange in this. For one thing, if Christmas isn't really about the gifts, then what does it matter if he gives the gifts back? Indeed, if he couldn't kill Christmas by stealing the gifts, then he can't restore Christmas by giving gifts), ergo his return of the gifts is ultimately a hollow gesture when it comes to the harm he tried to inflict. Hmm. So does this mean the Grinch still doesn't get it? Well, no.
By taking the gifts back, the Grinch is atoning for his sins. He is trying to make right the wrong he has done. But the real atonement isn't in the return of the gifts, it is in doing so publicly. Basically he is submitting himself to their judgment, and in the process is seeking forgiveness. Had he simply left the gifts at the edge of town, he would not have been redeemed. Thus, the meaning of Christmas according to this story is that the Grinch can be redeemed, and if such a villain can be redeemed by atoning for his sins, then so can you. All you have to do is seek forgiveness.
Now we get more complex.
● Who's The Grinch: Finally, there's one last lesson, which is probably the hardest for most people to see -- what made the Grinch into the Grinch and set him off on his life of crime was his intolerance for the happiness of others. The Whos never did anything wrong to him, but he came to hate them. And the reason he hated them was that they had something he did not, they had happiness. What's more, they found their happiness in something he did not understand. This is the same impulse that gets people complaining about "those kids today." If the Grinch had focused on his own happiness and had been happy for the Whos that they had found happiness, rather than being upset that others found happiness in things he did not and trying to bring down their happiness, then he never would have woken up one day to find that he was alone and in desperate need of redemption.
That's an awful lot of layers to stick into a cartoon, but it's all there.