A person who cooks professionally or skillfully. 料理人 is a neutral, common term for a cook or chef, without specifying rank.
He is a cook at a first-class hotel.
To become a cook, you first have to learn how to use a kitchen knife.
He wants to become a famous cook in the future.
She works as a cook at this restaurant.
He is known as a first-rate chef.
She has aimed to become a cook since she was young.