Many different structures, such as this one, are designed for entities to walk around. There are two commonly used ways to spawn entities. First is the manual spawning code and the second option is using a mob spawner.
It is possible to manually spawn a mob in your structure.
The advantages of manually spawning an entity are as follows:
It’s the easiest way to spawn an entity.
It’s the easiest way to only have a single copy of the entity.
It doesn’t require you to place an extra block. ...