HERE’S WHY THIS MOMENT IS A STRAIGHT SHOT TO MY HEART:
The heart of Chibi-Usa’s problem is that she doesn’t know how to grow up, she literally is paralyzed as a young girl because she’s so terrified of not being able to live up to her mother’s legacy. She’s subconsciously frozen herself in this form because she doesn’t think she can do it, because she can’t manifest her crescent mark, because she can’t be an elegant lady like her Mama.
That’s why Endymion encourages her to do a proper greeting, why he makes a point of being gentle with her, and why he praises her for taking that first step, that she did a good job with it.
We don’t see much of what happens in those ~900 years of Chibi-Usa not growing up, we don’t know how Endymion and Serenity handled it, but what little we do see is exactly like this: Endymion encouraging her and telling her she’s done well, he’s giving her every indication that she’s shown good judgement and can do proper greetings to make those first steps to being a wonderful lady.
It obviously can’t solve the problem for her, but it’s never been because her parents ignored her or didn’t care or didn’t encourage her. (And this part of what makes Chibi-Usa’s story even more meaningful to me, because it’s about her and her feelings and how she sees herself, that journey through that. It means more to me because it’s not some outside source to be fixed, but something in her that she has to work through, just like it’s something in me that I’ve had to work really hard to deal with.)