I live in a pretty hot climate, but it’s only really unbearable at times due to shoddy building and bad urban planning. Even then, summer can be difficult.
I can’t imagine what it’s like on the equator, especially in dense urban centres. What’s Mumbai, Bangkok, or Singapore like at the height of the wet season?! How do millions of people function day to day?
I live at the equator and it’s always ~28 degrees celsius where I live. You can get almost any temperature at the equator so that really isn’t a test of heat. Here in Colombia if you go down the mountains towards the coast or jungle it gets hotter. There the houses are built with lots of natural wind tunnel effects to keep them passively cool. When you’re outside in the heat you just get used to it. When I was in Iraq it took us a few weeks to really get used to it but even at 50 degrees celsius you eventually build a tolerance.