Which children? Did Hamas target children like Israel does, or were they unfortunately caught in cross fire while they were fighting against their genociders?

Incorrect. Hamas, in accordance with the Quran, believes it is possible for Muslims, Jews, and Christians to live in harmony. Furthermore, in their updated charter they explicitly reject targeting Jews for simply being Jewish:

Hamas affirms that its conflict is with the Zionist project not with the Jews because of their religion. Hamas does not wage a struggle against the Jews because they are Jewish but wages a struggle against the Zionists who occupy Palestine. Yet, it is the Zionists who constantly identify Judaism and the Jews with their own colonial project and illegal entity.

Hamas rejects the persecution of any human being or the undermining of his or her rights on nationalist, religious or sectarian grounds. Hamas is of the view that the Jewish problem, anti-Semitism and the persecution of the Jews are phenomena fundamentally linked to European history and not to the history of the Arabs and the Muslims or to their heritage.

I'd be a little mad at them too if I were in their situation.

I do agree that conservative Islam is partially to blame for the violence and terror but so is conservative Judaism. The conservative jews think it's their God given right to take the homes of the Palestinians and rule over them. Religion is fueling the fire on both sides.