I always heard it was the rectal temperature of a cow, but that's not what wikipedia tells me, so someone probably made that up. One advantage of the Fahrenheit scale is that the range from 0 to 100 roughly corresponds to temperatures people normally deal with.
After moving to Europe I am completely on board with the simplicity of the metric system, however I do prefer the Fahrenheit scale for exactly the reason you described above.
A human will face winter weather conditions from 0-32F which converts to negative values on the Celsius scale (not practical).
On the other end of the spectrum for summer time conditions, there is a wider range of values to ascribe to changes in temperature from 60F-100F or approx 16-38C.
Why is it not practical? We're taught in schools that water freezes below 0C and boils above 100C thus more than 0 = hotter, less than 0 = colder, more than 100 = you're melting. If you wake up and see less than 0 on thermometer you know it's freezing time.
Am I missing something, or are we just adapted for very different climates? Freezing is "wear a sweater" to you? I don't own a winter coat, but if I did it would come out of the closet somewhere in the 5-10C range.
I'm also willing to admit that this is probably a case in which whatever system you grew up with, that's what you will prefer and no argument will sway your opinion in the other direction. (Although the metric system does have clear advantages)
Pre-industrial levels when we were still coming out of significant cooling period. In every other period of human history, increased average temperatures have coincided with golden ages. Depending on where you peg your baseline for what "normal" temperatures are, the projections can look more or less scary.
I'm suspicious of anyone attempting to boil down the operations of such a dynamic, chaotic system as climate into simple cause and effect. There's so damn many things that feed back on each other, and that's just the tip of the iceberg that we think we understand. Much more research needs to be done.