Why is our body warm?

Answer

Our metabolism, that set of thousands of chemical reactions in our body that are necessary to be healthy and function properly, works best at a temperature of about 37°C. That may be a degree more or less, but at extremes we start to feel less good.

For example, if your body cools down very strongly, your metabolism will slow down and your organs will not have enough energy to work normally. In the end you can die. Even at too high temperatures, your body will work abnormally and you can eventually die. This was known, for example, by soldiers who had to do heavy physical exertion in high temperatures. The body temperature could rise sharply, the liver eventually stopped working and they started to break down their own muscles. This could lead to renal failure and eventually death.

Our body temperature is therefore necessary for all functions in our body to work normally.