Very useful if you want to survive in the wild

And those are the two most likely to die if stranded in the wilderness

(Sorry I am late) In hunting class instead of shelter they say heat.

Heat's probably a good description for normal things. Unless you're in the desert, in which case im not sure you need more heat as opposed to shelter.

At night you will most definitely need heat! But good point during the day, although for that all you need is water to continue sweating

Depends on the heat really. Water and sweat work well, but you can still get too hot and suffer from heat stroke even while hydrated.

Well then that's shelter you need it for shade if you're in the desert