No. Writing about sexual content involving animals is not ethical as it goes against basic moral principles and respect for animals. Animals should not be objectified in such inappropriate ways.
I'm not very familiar with this specific 'kangaroo man dreamtime story'. But generally in Dreamtime stories, they often involve the creation of the world, the origin of certain animals or features. Maybe the kangaroo man in this story has some special powers or a role in the creation related to kangaroos.
The little kangaroo statue in Pulp Fiction could potentially have been a visual metaphor for something, or perhaps it was just a quirky addition for aesthetic purposes. Without a detailed study of the film, it's tough to determine its exact significance.
One way is through strict content moderation on various platforms. They should have clear rules against this type of inappropriate content and enforce them.
The origin of the kangaroo's pouch is a subject of many tales. One popular belief is that it was bestowed by a mythical being to aid the kangaroo in its journey through life. Different cultures have their own explanations, but no one knows for sure.
The story could vary. Maybe the guy was in a dangerous situation and felt the need to punch the kangaroo to protect himself. Or perhaps it was an irresponsible and cruel act. Without more context, it's hard to say for sure.