This is a case of modern morals trying to square a round hole.

Here's what the new American Bible standard says (which is considered the most accurate English translation by Bible scholars)

If there is a man who sleeps with a male as those who sleep with a woman, both of them have committed a detestable act; they must be put to death. They have brought their [j]own deaths upon themselves

That's it, not man and child but man and male. As in, lumping in homosexuality with pedophilia (that old chestnut).

To my understanding this difference between man/male just equals homosexuality and homosexual pedophilia. If it were to protect kids from pedos, it surely would use a word describing children, not male.

If the verse is against pedophilia ("man shall not lie with boy"), why does it say both the rapist and the victim needs to be killed?

Except they had a Hebrew word for boy which the author choose not to use. Making the verse general. The author intended to say any adult man who has sex with any male of any age.

It would be like me saying "do not use your stuff to steal property". Property includes stuff.

To be fair, we didn't become conscious of uiquity of fucking children (and that it might be causing irreparable harm) until the late 20th century. Before the 1990s in the US, it was a social convention to let each household raise kids without checks, so if you hear violence from your next-door neighbor's house, you leave it be.

The term incest technically covered any familial sex, but in the 1970s when discussed was about daddy (oft inebriated) having his way with his daughters. It was assumed child sexual assault typically was of this kind (and everyone's doing that) so it was disregarded. (other pairings were going on, but we made Alabama jokes about it. Or Mississippi jokes.)

Then it came up in some public cases that not dads and not dangerous strangers, but other familiar adults (teachers, caretakers, ministers, etc.) were getting handsy with the kids. When it was investigated it was found to be so ubiquitous that there were concerns full prosecution of all the child molesters would drastically reduce the workforce, and cause an economic crash.

This was the backdrop for the 1970s-1980s Satanic Panic, because we just couldn't process that everyone was diddling kids (1in 3 women and 1 in 5-9 of men in my generation were sexually assaulted as kids, and it's intergenerational ) so the whole story that satanists were ritualy sex-abusing kids became popular, inspired by The Exorcist and the Hollywood Satan-movie knock-off craze.

For more fun and existential horror, check out the Behind The Bastards pod two-parter on The Satanic Panic.

Really doesn't matter in Christian thought. Paul looked at all the laws of Moses, kept a few of them, and tweaked a few other ones. Which includes homosexuality. Which he attacks twice.