IDK, most of the ones I remember from when I was really little, like give a mouse a cookie age, were about animals(either fables or simple descriptions of animals) or were about parents and children loving each other. The fables were propaganda kind of, but for things like "take your time on things" or "don't listen in on other's conversation," and if your parent is reading to you about how a relationship between parent and child should be and it shows the parent caring for and loving the child and the child being loving towards the parent that's propaganda in favor of something good. There was a lot of heteronormativity and no overt opposition to capitalism, but I would not really call any of these blatant propaganda. If you're talking about older kid's books, like something a kid would read on their own, there's more opinion and worldview present because there's more to work with, but I don't think the driving thought is always manipulating people's thinking. Rick Riordan wrote Percy Jackson for a couple reasons: one was because he'd started telling it as a bedtime story and thought it seemed like an idea worth expanding on for more kids to enjoy, another was to tell a story with a neurodivergent protagonist(I can't recall if it's he, one of his kids, or both that has ADHD, but the reason demigods struggle with ADHD and dyslexia is to have heroes that neurodivergent peopel can see themselves in), and also to expose more kids to Greek Mythology. The driving motivation is to share a cool story. If you look at something a little more low brow, Captain Underpants, the driving idea seems to be making a story that the author wanted to read at that age. Diary of a Wimpy Kid was meant to be nostalgic literature for adults and spiraled out of control for the author. P. B. Kerr wrote the Children of the Lamp(lot more obscure but a big part of my childhood) because he had what he thought was a cool idea about djinn that worked better as kid's adventure novel than adult literature. I guess there are some cases like the wizard books where the author explicitly saw it as a ticket out of poverty, but by and large people write children's literature to share a cool story.