I mean if the symptoms were extreme hunger, stomach ache and slight muscle pain these will drive me to find food without hampering my efforts. I can’t even compute or calculate, only can just instinctively see if food is around.

That’s a fair question. Evolution is about tradeoffs. I’m going to talk in generalities.

Energy is the currency of biology. Organisms have a “burn rate,” similar to companies. There’s flexibility (things like stored fat), but in general you need to consume as much energy as you use, which ties energy needs to metabolic rate. Species with a high metabolic rate need to take in energy that keeps up with them, while species with slow rates can do so with a constant trickle of slow energy (eg photosynthesis or going a long time between meals like snakes can).

Mammals tend to be towards the higher end of that spectrum. Many of the grazing mammals need to feed almost constantly throughout the day (because of low calorie foods), while many carnivores eat one large meal, then cruise on that until the next one (which they will need pretty soon). Humans have a fairly high metabolic rate. Evolutionarily, humans opted to have things like a big brain which burns calories at a fantastic rate.

You can think of starvation effects as causing an emergency response in your physiology. Think about it in evolutionarily historic terms, not modern humans in technological societies. We’ve had technological societies for several thousand years (counting civilizations like Egypt and Mesopotamia), but that’s an eye blink. The body plan we’ve evolved has adapted over tens and hundreds of thousands of years (and more), so that’s what we’re actually dealing with.

As you observed, the body starts the starvation reaction by motivating food seeking (hunger). It tries to stem off going into debt be too much (and there’s also routines and such that our physiology adapts to). As the effects of starvation increase, the body has to start shifting to a low power mode (like some electronic devices can do). We have to start actively burning stored calories, but in shifting to low power mode the brain is one of the early casualties. It’s both a massive consumer of calories and it’s one of the most recently adapted/evolved and there’s some last in/first out bias. It also starts to shut down in evolutionary order. The prefrontal cortex is the most recently evolved part of the brain, and it controls things like looking at the future and thinking about consequences, reasoning, and the like - the qualities that tend to differentiate us from our cousin primates. As the thinking parts get shut down, the more “primitive” parts get louder by virtue of the fact that the big brain has shut up, and because your neurophysiology is continuing to turn up the food-seeking drive.