I recently heard a woman on the radio telling the presenter that kangaroos are peaceful animals and that she had learnt a great deal from them. By and large I agree that they are peaceful but they do fight and there are plenty of records of attacks on humans.
There have been some studies on kangaroo fighting, a couple of easily accessible ones can be found <HERE> and <HERE>. If you’re into lurid accounts of attacks on humans you can find a catalogue of them <HERE>. I mean, kangaroos kill people don’t they? Well yes but almost exclusively by way of motor vehicle accidents (and even in those cases there’s not always a real kangaroo involved). A hunter in New South Wales was apparently the only human killed in combat when he tried to rescue his dogs back in 1936.
Kangaroos will fight each other for resources such as food, water or access to females in oestrus. These tend to be serious engagements. Much more commonly the fights are between youngish males with no obvious prize at stake and end without significant harm to either. Mothers will also “fight” with young male offspring perhaps by way of training them for future bouts.
Males have impressive arm and chest musculature, an example of sexual selection. Skippy was clearly a female.
Scratching, pushing, punching and downward raking kicks seem to do little harm through thick fur. People of course are not protected in that way. When you watch a fight it looks as though eyes and gonads are the structures most likely to be injured.