Well, as I say, it all depends. Punching someone requires you to
be in contact with someone, molesting someone requires you to be in
contact with someone, raping someone would require you to be in
contact with someone.
What's the difference?
For punching, you used force. Depending on age and other factors,
amount of strength used is enough to kill.
For molesting, I'm not going into details. But the psychological
harm done is enough to push people to death. Not literal push, but
a psychological push.
For raping, no details again. But someone can die if forceful rape
is used. If the person survives, psychological harm may be enough
to cause death.
All in all, seeing the starting and the ending, it makes punching
no different from molesting and raping. It starts with contact, and
may end with death.
Next on permissions. I don't think giving examples help, but I will
still give.
You originally own a dog. Someone comes along and says it's cute
and start touching it. Nobody gave him the permission to touch your
dog. You obviously will dislike him.
Now back to your own body. If you are some sensible human, you will
know what's self-respect.
All animals are blessed with this instinct, and they will attack if
another animal is trying to do funny things.