Metric works fine everywhere it is used. It's just what you are used to. American engineering isn't any better or worse than engineering elsewhere. There's no inherent advantage to using a different way to measure stuff that you can objectively point at.

The history of the Fahrenheit scale is actually quite fascinating. It's one of the less famous things to come out of the Dutch eighteenth century scientific community. Daniel Fahrenheit picked a few reference points to calibrate thermometers. None of these have anything to do with your level of comfort. That was never a thing or an intention.

Zero was the temperature of a particular mixture of ammonium chloride and water and ice (a brine basically) reaching an equilibrium. The second point (30) was picked as the temperature of water with ice floating in it. The main point was to make this somewhat of a repeatable process. Basically water with ice in it has a very stable temperature because the transition from ice to water takes a lot of energy. Tossing in some ammonium chloride in a known quantity gives you a second point of reference that is different enough that it is meaningful.

Daniel Fahrenheit was using those two points to calibrate mercury based thermometers. He came up with a third reference point: the temperature you get when you insert a thermometer into your mouth. This was originally supposed to be 90 degrees. Later it was determined to be 96 and we now know it is 98.2 degrees. In other words, he kind of messed up there by picking something a bit harder to measure.

The final reference point that Daniel Fahrenheit worked with was the boiling point of mercury. Which he put at 300 degrees. The scale was redefined several times according to progressive insights regarding e.g. the notion that there are about 180 degrees Fahrenheit difference between freezing and boiling water.

The latter is of course an attempt to reconcile the scale with the centigrade scale which is based on the freezing and boiling temperatures of water. That's technically also somewhat imprecise of course but quite easy to figure out. Basically take water, put ice in it, wait a bit. That's your zero point. Then put it on a fire, wait for it to boil. That's 100. Put two little markings on your glass tube with mercury where that happens and then divide that into tens and again into tens. That's a repeatable process for making a thermometer. Not super precise of course because it depends on air pressure (later of course factored into its definition). But if you are making thermometers, that's pretty easy to do if you are an eighteenth century instrument maker. You need ice of course but that would have been a commodity much of the year where Celsius was living (Stockholm).

For better or worse, the metric system actually uses Kelvin which simply is the Celsius scaling (or centigrade as it was called originally) but adjusted to absolute zero −273.15°. That last adjustment by .15 degrees happened only fairly recently actually. Fahrenheit only continues to exist as a derived scale from that. None of its original reference points are precise enough to matter these days. That's true for most remaining imperial measurements: they are defined very precisely in metric units. You can measure feet with your feet of course. But only if you don't care about precision. Any self respecting engineer uses more carefully calibrated instruments.