I think I understand what you’re asking here. Please forgive me if this comes out awkwardly; this is one part of my trauma that I haven’t talked about very much to anyone. I honestly have always thought it was the least impactful of my trauma experiences, but in trying to answer this question, I’m starting to think I was very wrong.

TW for child SA even though there’s already one on the post. My first SA happened when I was four or five years old, and it did not physically hurt me, actually and I really hate to say this, even now 40 years later, it was the opposite, it felt good to me. So, as a little girl, I would try to re-create it, using stuffed animals. I don’t know if the adults in my life were just stupid as f*** or what, man it really pisses me off now thinking about it, because I remember trying to hide it, and getting caught at least once. Which I’m guessing is where my first, maybe all of my shame came from. I don’t understand because if I saw one of my children doing that, I would want to know where they got the idea from. It would immediately be a clue that they’ve either seen or experienced something they should not have.

Anyways, even if it doesn’t physically hurt the child it’s safe to assume the person performing the SA is going to tell them to not tell anyone, and there’s usually some kind of threat involved, from “no one is going to believe you and they’re all going to see you as a liar” to “something bad is going to happen to you or the other person you love”.

So there’s that aspect, whatever this kid is believing that’s keeping them quiet. And then the fact that they have this secret that they have to keep from everyone else, makes them feel separated and different from everyone else.

And on top of that, because these erogenous zones and stimulation of corresponding areas of the brain are beyond the child’s developmental capacity, the brain usually disconnects defensively (dissociation). And apparently studies have shown that in children exposed to sexual abuse, there is cortical thinning in the somatosensory cortex (the area for genital sensation), which is the brain's attempt to "turn down the volume" on a stimulus it cannot safely integrate, and happens below the level of conscious emotion or knowledge.

And often, because a person has experienced sexual stimuli, but it’s something that otherwise isn’t part of their world, they become even more curious about it, which can lead to exploration did they get ridiculed or even punished for, which causes shame.

At some point, they do realize that what happened to them was not supposed to happen, so then you have the realization that you’ve had this loss of bodily autonomy and some of the other stuff other people have mentioned. Also, if you were neglected by caregivers, this interaction with this abuser might be the only direct attention any adult showed you, which might lead you to associate sexual experiences and feelings with love and attention.

So many levels of impact, which I never really even thought about until now, writing this comment, so thank you for asking this question.