So humans feel cold at 0F and hot at 100F?

In aggregate this is absolutely true, though not the point anyone is making.

Humans start quickly dying at something around 32F and 180F

Humans will die of dehydration or heat stroke quite quickly at temperatures well below 180F. In fact that's far hotter than the hottest recorded temp on Earth (~135F/56.7C) (not including human-made environs like a sauna or outliers like an active volcano) so I'm frankly not sure what point your even trying to make here.

Fahrenheit is complete nonsense. It has nothing to do with humans.

The latter statement is manifestly false. Fahrenheit was originally supposed to have 90 degrees as the average humans body temp (no clue why 90 and not 100). Due to inaccuracies in measurements of the time, It was later changed to 96 and then 98.7. Still no clue why not just 100, but the fact remains it was based on human body temps. The zero point was selected using the freezing point of a brine mixture. No real defending that one, it was pretty much arbitrary.

And considering humans are mostly water Celsius seems a much better fit.

But we aren't just water. In any case, humans are rarely at boiling temperature. My ideal temp scale would have 0 at water's freezing point and 100 at a humans body temp.

Humans start quickly dying at something around 32F and 180F.

They do? 32F is 0C, it very routinely gets below freezing in many inhabited parts of the world, including the US, and people get along just fine with some precautions. Likewise with 100F (not sure what 180F has to do with it). So yeah, 0F and 100F are around the extremes of what humans regularly experience. (though it does, of course, get hotter and colder in some places).