Lol

And at the root of it all is this magical thing called quantum mechanics; wherein particles that don't even exist ... amount to observable, tangible, forces? It's really complicated

I don't really disagree; it is an incredibly complex, useful, and absolutely necessary system. But with the use of medications, we can prevent a whole host of side effects from the immune system. Why wouldn't you if you could? I don't recall ever saying any of the things you're implying I've said.

We have a pretty good idea of how the immune system works; but we know less about how it works than we do know how it works (as far as we know). It's mostly reducing the amount of thermal energy lost, but doing "more work" does inherently increase thermal energy. So it's probably a balance of all of that.

Here's a good YouTube channel that covers quite a lot of the immune system in a very layman's kind of way.

Mostly high level fevers; but our bodies maintain a "body temperature" for optimal performance for a reason. Low grade fevers are not much to worry about.

"Heat/thermal energy" is simply a measure of how fast tiny little particles are moving; the more work (energy) being done, the faster (hotter) the particles are moving. There are lots of reasons that cause the heat to go up (as outlined by another commenter here). Our bodies are doing A LOT of work; our bodies are constantly generating heat. This is why we sweat; heat transfers to the sweat and the sweat evaporates into the atmosphere, thus cooling us off. You can think of sweat like a biomechanical liquid cooling system. Under Armor clothes for sports works by absorbing the sweat into the material, which increases the surface area in which the atmosphere can evaporate it, cooling us off even faster. To raise our body temperature, all our body has to do is regulate how much energy is being lost to the atmosphere versus how much energy is staying in the system (our body); which it can do in all sorts of ways.

Our immune system is a bit outdated. Typically, we can treat the ailment better ourselves with proper medications and procedures. Back when our immune system developed, we didn't have any of these things. A fever damages your body, your brain, and your immune system wreaks a lot of collateral damage. In our early stages of life, a little collateral damage is better than dead. Nowadays, we don't need that collateral damage because we can just treat it ourselves.

Our immune systems are not perfect, but it's better than nothing.

The 3 phases of fever

Fever is your body’s way of letting you know something is wrong. In a way, the fever is helping to fight off your infection.

This happens in 3 phases.

Your body reacts and heats up

Your blood and lymphatic system make white blood cells, which fight infection. When you have an infection, you make lots of these cells. They work faster to try and fight off the infection.

The increase in these white blood cells affects your hypothalamus. This makes your body heat up, causing a fever.

In the early stages of a fever, you often feel cold and start to shiver. This is your body’s response to a rising temperature. The blood vessels in your skin tighten up (constrict), forcing blood from the outer layer of your skin to inside your body where it is easier to keep the heat in.

The outer skin layer then becomes cool and your muscles start to contract. This makes you shiver. Shivering produces more heat and raises your temperature even more.

The fever levels off

In the second phase of a fever, the amount of heat you make and lose is the same. So the shivering stops and your body remains at its new high temperature.

Cooling down

Your body starts to try and cool down so that your temperature can return to normal. The blood vessels in the skin open again, so blood moves back to these areas. You sweat which helps to cool the skin, this helps to cool down the body.

This phase of a fever may or may not happen naturally. You may need to have some medication to start it off, as well as treating the underlying cause of the fever.

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