That's because "I'm sorry" is essentially short for "I feel sorrow". What it means specifically can differ depending on the context. We have lots of examples of phrases that work like this, for example: if you end a relationship with someone you call it "breaking up" with them. If you pass through a tunnel during a phone call and can't hear the other person very well or the call drops, they're "breaking up". That's because something "breaking up" can refer to it falling apart or being severed. When you apologize, you feel sorrow over your own actions and/or the hurt they have caused. When you console someone grieving, you feel sorrow for their loss. This, like puns, is not in any way exclusive to the English language.