Food chain is the basic circle of life.
It depicts how each species, each category of existence, is dependent on other category/species for their survival.
It starts from plants, how cattles and other animals like deer, etc., are dependent on plants, other animals like lion, etc., who have a carnivore diet, are dependent on these lower belt of animals.
Similarly, human beings are also dependent on plants, those who are herbivores. On the other hand, their are human beings, who are omnivores. These depend upon flesh, meat too.
I hope this answer helps!😊