So if a slave killed his slave master and all his master's families and friend, he is proclaimed as innocent?
If a slave lived for hundreds of years and they only seen the bad in people do you think they are wrong for viewing everyone bad? To them kids are nothing more but younger evil humans who will grow up to be like everyone else. Gaara actually had this mindset, he grew up hated and feared by his clan, his father sent assassins after him when he was really young and he grew up not knowing love or anything good of humans. He killed all those who attacked him and as he grew he didn't feel like he was alive until he killed someone but from what we seen he only killed those who attacked him or bothered him in a bugging way. Plus the hatred from Shukaku was influencing him.
As you can see anyone who suffer from nothing but negative interactions with someone or something for years would grow up to hate or not care about it. Humans are destined to kill Humans, this is a real life fact and is seen in mangas. Most of the Bijuus destruction was done by humans, the Sage even said the Bijuus were meant to be protectors but things didn't turn out that way.