... as if they don't have even stronger biases than us.

Also, your knowledge on the sexual expression of little girls is wrong as historic examples are not limited to little girls being used as sexual playthings. I would never ever use such examples anyway. Check out some anthropological research on cultures that are open to child sexuality. Historic and anthropological examples are only important in so far that they show that young girls (and children in general) are sexual and do seek sexual interaction with peers and older people.

An injustice that is corrected overtime is still an injustice and regardless it has its effects on the person that do not always just disappear.

Regardless parents can allow a child to express themselves sexually and guide them when needed. I don't think anyone here is suggesting we just let little girls fuck whoever they fancy whenever they want with no guidance or input from someone with more knowledge or experience. The current laws and social views do not support this and force the opposite on people. Which is just as wrong as forcing people to make their kids sexual.