This is completely common and normal toddler behavior, and some of it, like hitting you seemingly just for fun, is developmental and will naturally fade out with time and appropriate redirection. It's a stage that is present with both girls and boys, although the intensity varies from one child to another.
Here are some reasons your child might hit or seem to enjoy hurting others or watching others be hurt:
- Toddlers are fascinated by cause and effect. I hit mom and her facial expression changed! I crashed toy cars together and it made a loud noise! I swung at the puppet and it dodged away! They are busy learning about their ability to affect and control their surroundings. Parents and familiar adults are a primary safe outlet for testing this fundamental concept.
- Toddlers don't really fully understand that other people have feelings or are capable of feeling pain. The "theory of mind" that allows children to realize that other people have a mental life separate from their own, with unique emotions, motivations, and preferences, will continue to develop over the next few years.
- They don't grasp the symbolic connection between smashing toy cars together and real traffic accidents, or animals hunting on TV and actual death. Like Pocoyo's duck, which is always back to normal in a few moments no matter how much it gets hit, your toddler won't be able to understand the finality of death or that there are potentially permanent consequences to injury.
- They don't have impulse control to stop themselves from doing things, even if they know it's not desired behavior. Impulse control can be taught as children grow, but has a major developmental component that a 2 year old has not reached.
- They don't know how to manage intense emotions. Frustration, anger, overstimulation, or even intense happiness and excitement can feel like too much for a little person who can't easily use language to express their feelings. They may lash out either to make their displeasure known, or just as an outlet for overwhelming emotions.
- Many normal, well-adjusted people do find "fantasy violence" funny. From slapstick comedy to Roadrunner cartoons to shooting video games and the viral "fail" videos online, lots of people do find it entertaining to watch others get hurt in a hypothetical way, even people who are not aggressive to others, would try to prevent others from being injured in real life, and otherwise show normal levels of empathy.
The best treatment for this issue is gentle redirections, explanations, and time. You can say something like "use gentle hands" and demonstrate how that is done; repeat each time he hits. Avoid spanking or similar, it is not effective and sometimes even reinforces hitting.