Back in time, humans and any other animal on Earth needed to eat. Food consisted of fruits and cereals, which are rich in carbohydrates. Carbohydrates are our main nutrients still today. As its name says, they are formed basically of Carbon atoms bounded to Hydrogen and also to Oxygen atoms. Glucose is one of the simplest carbohydrates, known and has 6 atoms of Carbon, 12 of Hydrogen, and 6 of Oxygen. Many carbohydrates (glucose, sucrose, lactose, etc.) are sweet, and for this reason they are also known as sugars. The second most important nutrient for early humans was probably protein, and hunting/fishing wild animals was the best way to get protein. Lipids, vitamins and minerals, and other nutrients needed to keep early humans alive were obtained from the vegetable/fruit and animal foods. But there is one thing missing—actually the most important one—water. A relevant point for this article is the way Homo drank water before and after fire discovery. Before fire was discovered, humans obviously had to drink water that was at "room" temperature, but after they discovered fire, humans were able to prepare hot drinks.
The ability to heat water probably made eating more enjoyable for early humans.

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Go to source: https://kids.frontiersin.org/article/10.3389/frym.2017.00027