This is because the Khajiit has a unique racial ability known as Claws, which essentially gives them a +12 on all unarmed attacks. Those are the number one-hitters when it comes to hitting. The furry, sneaky cat people are described as super thieves and assassins.
The best-unarmed combatant race, by far, is the Khajiit. Now, while one might instinctively consider the Orsimer Orcs, the Redguard, or even the Nord to act as a viable combatant option, you’d be wrong. First thing’s first, you’re going to have to determine what race your character is.