First Person Cameras
First Person cameras are set so the player sees the game environment through the characters eyes.
This type of perspective is used to make the experience more immersive - like the player IS the character rather than controlling the character. As the player can't see the character (or can only see a little bit of the character e.g. hands), it bridges a gap between the player and the character meaning they can relate to them without having to actually share any traits with the character.
For this reason, 1st person often works best with games where the emphasis is in the world and what is happening, rather than the character and their backstory. It's more about experiencing the game world and events unfolding in front of them, instead of learning the character and associating them with the game. Physically seeing the character would help the player form a consistent image of the character in their mind, but that would re-affirm the character as a character rather than the player as the character.
First person is most often used for shooters and action games. When the player experiences something that would be exhilarating, scary or nerve-wrecking to the character, they feel it more themselves in first person, while in third person they would feel that it is more happening to the character, not to themselves. As action / shooter games have a lot of adrenaline filled moments in them, it makes sense to use first person to create the most immersion and get the biggest emotional response from the player.
In games that use weapons which need a skill of accuracy to use sufficiently, first person is very useful. First person makes aiming something like a gun, or bow and arrow easier to aim as the player is using a realistic trajectory, while in third person or top down it might be difficult to take in to account the trajectory in all angles x, y ,x, etc. Because of this, aiming with weapons like these in 3rd person or top down games take less variables into account, and will usually just fire in a straight line.