Depends what you mean by essential. If you mean essential nutrients then they are those that can't be made by the body.
It absolutely requires protein ie 9 amino acids (10 for children), but only 2 fats (omega 3 and 6) and a whole raft of minerals and vitamins. Unlike most other animals we can't make vitamin C.
Carbohydrates are not essential in that sense, however many essential vitamins/minerals are in foods that are high in carbohydrates( Unless you eat liver you won't get any Vit C without also eating carbohydrates)
Fibre is not traditionally considered as a nutrient but we are discovering more of it's properties and it is considered by many to be an essential part of the diet ( most of us eat tiny amounts compared to most people in the past)
.
Eaten by themselves many fats provide little but calories , some are almost as devoid of essential nutrients as sugar.. (check out the nutrient profile of
coconut oil)