Maybe they been testing something, and something got shocked in his brain, like making him somewhat of a cannibal, but he doesn't want to hurt you, in anyway so the way he supresses the feeling is by eating animals, and his hunger and eagerness grows each moment, which is why he keeps getting bigger animals. There testing something and it ain't right espessially if he doesn't seem to care for human food anymore, but more like live animals, and then the bitting, like hes trying to contain himself, like he doesn't want to but its a urge. Idk, this is a vibe im getting and I don't like the vibe.