Really interesting question 🙂 I think, it has something to do with our ancestor’s enviroment in Africa, because kind of logic to have similar temperature as your enviroment, otherwise you will either lose energy or you will be boiled 😉 Later, when human began to wear some sort of clothes, this was no more so important, so that temperature has stayed, althrough people live from the poles to equator
(althrough I think there are some differences between nations;)

when i go to a hillstation i have seen people wearing minimum clothes while i would be wrapped in what not’s

basically earlier the mankind must have started life along the equator in places like india, egypt, china and africa. and migrated to cooler places lot after the wheel and the availibility of clothes from animal skins

It is a very good topic to have our brains pondering over for an answer. We have been learning about this right from the childhood but never gave a thought why it is so. It would be great to have some interesting thoughts on the topic in this thread. I think that the blood essential for our living contains a major portion of water and at this temperature the flow would be at a normal pace, that could be the reason.

doesn’t set in too much