There are three people involved in this entire thing.
1. Users like Vorden: These are people who die while using the VR game and the most important of all, they were chosen by the Creator (Chapter 13). They are very scarce and it's likely that Vorden is the only one remaining after a cataclysm. (Chapter 13). It is said that they are responsible for the NPCs technology like Crico technology. (Chapter 3 and Chapter 17). They are like a mix of NPCs and players.
2. NPCs like Layla: They reside in a particular world in the game. They are known playable characters like you see in GTA. Some NPCs have human counterpart in the real world like Layla. NPCs aren't smart(Chapter 3), because they we're programmed smart. They are strategically smart, but compared to an average human, they fall short. That's why the students were so stupid mathematically. The NPCs also don't age said in chapter 3.
3. Players like Tina: these are humans who log into the game from the real world. They are normal human beings who play the games. The giant in Chapter 4 is also an example of a player. Unlike Vorden, they don't reside in the game but in the real world. They play the game either through VR, computer, console or mobile(Chapter 26). For the most immersion, they use VR. They can communicate with other Players in the same game world/Instance as they are in. They can also create Instance and can invite others to play there. Just like Roblox or Recroom.
There are also different worlds in the narrative. Three to be accurate. (You can join my discord server if you ever anymore questions, I will answer).
1. The normal world i.e where you and me live in. Chapter 14 and 15 gave glimpses of the real world with mentions of places like America, Asia and Tokyo.
2. The NPC world i.e where Layla (NPCs) live in. The place that uses terms like 'Dominion' for country and the likes.
3. Game World (Instance World): This is basically the game (different games, just picture Roblox and Recroom) itself. It includes where Vorden fought the giant (Chapter 4), where Vorden, Tina and Just_Cooked are (Chapter 20 downwards). This is where users, NPCs and players interact in different instance games.
A player can not be in the NPC world and can only be the normal world and game world. An NPC can not be in the normal world and can only be in the NPC and game world. A user can be in the normal world when he is unconscious in the NPC world and can also be in the game world.
Vorden: the main character. 27 years old. A teacher.
Layla: There are two versions to her. The real world version, the woman and the counter in chapter one and the woman Vorden gave the Lady Trousers to in Chapter 14 - Chapter 15.
Tina and Just_Cooked: These are normal human beings like you and me who log into the game to play. They are not in real danger like Users as if they die, they'll just lose some points. Users on the other hand, when they are killed they die for good.
Since everything was moving so fast, it was getting difficult to process it all. But now, after eating the fruit both the readers and Vorden will have a clearer understanding.