Considering how there hasn't been shown any violence due to inner conflicts (just the recent jaguars, and even then it was covered up), it seems murders and the such is not common at least in her lifetime, just harrasement, so even if passive I wouldn't call her naive.
But still it's the royal family, there's bond to be signs of their clear hatred and they don't seem too keen on keeping it hidden. Is it really a surprise that her mom was murdered? Did she never question anything around her, her mom's death?
I think that's giving too much faith of a child with her context. The royals were all she had left, and they told her it was a punishment done upon her by the heavens basically, they were the adults and family she could trust, as her own servants even if loyal are completely ignorant of these issues. There was no reason NOT to trust them, as even if she hated their treatment, she saw them as benevolent for even allowing her to stay in the palace without her mother's concubine statud, not even liking her to begin with. It was only after getting to see the outside world, gaining some amount of courage and a wider mindset that she could accept the idea of such evil, that killed off her mother yet didn't kill her to enjoy her torture and then sell her off, all when she presented no political threat to them.
Or so I'd rationalize it, but maybe the author did characterize her to be so naive, it just feels wrong to me.
Isn't she a lil... Naive? I mean she knows they hate her n her mom but she is still so surprised about their actions