Sharks don't usually bother humans. Something must be odd in Oz for now. It's really unusual for a shark to bite a human who is under water. On the surface seems to be the usual location. Even so, there's a reason people use shark cages when some sharks are around.
I have seen bull sharks like what the article says attacked one person. I saw them at about 80 feet in Costa Rica. There were a number of them, and about half a dozen divers were with me looking at them. It's pretty common for divers to go looking for bull sharks. They are bit, impressive animals. Reef sharks are much more elegant looking. They also have a sense of humor. One of them rolled its eyes at me, as if to say "sheesh, divers again?" I have also been pretty close to nurse sharks and another kind of shark I can't remember the name of. I should remember the name, because those sharks were enormous. I'm hoping to see a hammerhead one of these days.
There are also relatives of sharks that are fun to see. I had a ratfish swim next to me for a pretty long time like a puppy. It was in shallow water, which is unusual for those. Ratfish doesn't sound especially attractive, but it was a fairly elegant looking animal with really big eyes, like a puppy. I don't have a dry land pet, but now I have a pet ratfish. I may never see that fish again, but it's still my favorite pet fish.
This isn't to minimize what happened or the fact that Australian authorities were absolutely right to close the beaches until whatever is going on settles down.