I think you misunderstand. 1.5C does not mean temperature everywhere is just going to rise by 1.5C.

This means altering of global and local weather patterns with unpredictable consequences. Some places will get much colder, some will get much hotter. Some places will dry out. Some places will see more tornadoes and flooding.

And some will get both hotter and more humid causing them to be absolutely uninhabitable, because of combination of 100% humidity and over 35 degrees C is basically lethal.

So if you think this is just a "thing", and "what's the fuss, you are going to have more sunshine", you obviously don't understand what the problem is.