Lets explain each in order.
Exodus 21:17: “whoever curses his father or mother shall be put to death”
First off, that does not mean that the offender is a prepubescent child. A forty year old man is a “child” to his parents, and some people even in their late 60’s still have parents (rare but true). So, to assume this is proving “violence against children” claiming the verse is somehow talking about children, which it is not. Do you have parents? Then you’re capable of being an offender.
Next, we need to evaluate what “curses” means:
Qalal – be of little account, to be insignificant, to be lightly esteemed, to make despicable, to treat with contempt, bring contempt or dishonor.
They were treating their (most likely elderly, assuming this isn’t directly talking about children) with contempt and in a way to dishonor them (a horrible thing in that day and age). It also says “curse” includes to despise ones parents and make their name despicable.
I fail to understand where you get child abuse from that passage.
Leviticus 26:29: “You shall eat the flesh of your sons, and you shall eat the flesh of your daughters”
This is a prophecy of what will happen if they walk contrary to God. In doing so, God will remove His blessings, which includes a fruitful harvest, and they’ll eventually resort to cannibalism.
God is completely against them turning against Him, and wants everyone to turn to Him, He doesn’t enjoy seeing anyone perish. (Ezekiel 18:23) This is not a condoned action, nor is it commanded. Its a prophecy of the evil that will occur if they turn against God.
Numbers 31:17: Kill all the little boys but not the virgin girls.
According to scholars, the significance of the “virgin girls” is because they didn’t partake in the pagan sex rituals that the adults most likely did, and the little boys would eventually rebel and threaten Israel’s national security.
Another interesting thing to note, even when the Bible says “utterly destroy everything”, not everything is utterly destroyed. For example, Deuteronomy 2:34 states that “we captured all his cities at that time and utterly destroyed the men, women and children of every city. We left no survivor”. Again, in the next chapter, we read that Israel “utterly destroyed … the men, women and children of every city” (3:6).
Do you know why? Israel attacked military forts, not general populations, in most cases. That’s why they could walk around Jericho seven times and still battle on the same day. Expressions such as “young and old”, “women” were ancient stock expressions for totality, not literal orders.
Interestingly, Deuteronomy 7:2–5 uses words like “utterly destroy” right next to “you shall not intermarry with them”
So, as we’ve seen, “utterly destroy every city” was rather a regular ancient usage of rhetorical language. Plus, the Israelites aimed to annihilate the Canaanite religion, not general population, and their military conquests were aimed towards military forts, not the general population. I’d recommend doing research into this topic, its quite interesting.