Book is about several students from different planets but all human on a school spaceship.
The main character is at least 2 meters tall. This comes into the plot because when they visit earth he has to pay a penalty for his weight. Although the school says they will pay it he ends up fighting in gladiator style games to earn the money back.
If I recall correctly he fights bulls, sharks (with a partner) and a genetically modified polar bear. Breaking a camera
This is There Is No Darkness (1983) by Jack C. Haldeman, II and Joe Haldeman.
The giant is Carl Bok, and he's not just extremely tall, he's a heavy-worlder, which is why he gets matched up with a bear. (IIRC, it's not clear that he actually breaks the camera fighting the bear. It's more that the fight organizer claims Carl broke it to get out of paying him.)
Quoting from the blurb on Goodreads:
Carl Bok is a citizen of Springworld, the heavy-gravity planet with monstrous and dangerous flora and fauna. Carl is well over two metres tall and weighs-in at 180 kilograms. Now Carl has won a scholarship to Starschool. He'll spend a year on this touring school, visiting sixteen of the colonized planets. This will be the experience of a lifetime.
It's tough enough for Carl as the poor scholarship student among the rich kids. His problems get worse when they arrive at Earth. Carl finds himself in urgent need of big money and, since he's a pretty tough guy, becomes a paid fighter. He has to fight dangerous and deadly human and animal opponents. His fellow students, B'oosa, Miko, Alegria and Francisco "Pancho" Bolivar, get caught up in his exploits. And then there are the aliens.
