it isn't a masterpiece
This flash wasn't that great in my opinion. The story was slow and empty. People have said the story is unique. It's not unique. The only way it's unique is that it lacks any complexity.
Story: creature has a wife and kid, creature goes to get some kind of food, while away wife is killed and kid is missing. creature gets angry, find monster, transforms, kills monster, cut open the monster and finds kid, then gets killed by monster as it falls over dead. kid probably survives but nothing says it does.
The animation wasn't ground-breaking but since you are only 15 that's fine. all I can say is keep working at it and think of a deeper plot, maybe add some different sounds, change the mood of the flash as it moves along.