Sugar is not essential for the human body.

There is no necessary carbohydrates, whereas you require some amount of fat and protein to survive. Consider humans surviving in cold area with literally no fruit except in Summer (at some extreme level: human thriving in area with no accessible plants to be directly ingested).

Fruits are not the enemy, but keep in mind their wide (mangos in Northern Europe!), year-long availability (strawberries in February!), along with their nutrition value (high in sugar) is a product of modernity.