Problem with Darwin’s Theory of Evolution ?

We have all studied that all the organisms on the earth as we see them are here because of the very basic principle of Charles Darwin which states that

All organisms are naturally selected by nature and there are always variations in a species which helps in exhibiting variations in traits and eventually lead to a stable species.

But the thing that’s bugging my brain is that,this theory explains why we start developing new characters both physically and chemically but it does not tell us what happened to the ones which did not do any good nor harm to us.

For ex. Emotions like laughter, in what way did they even have to be selected? Assuming that they did develop somehow, then why did the traits which DO NOT express emotions like happiness have to disappear.

We all know that,everyone today knows what happiness exactly is right? Some people would just say that, we would just start developing what it is.If you think that is the answer,then please tell me why there is “fear”.We don’t have to know or someone tell how fear is and what it feels like and even if we did try to teach them,it won’t do anything good till they actually experience it!

Another answer that people might put forward is that,probably,there is no traits associated and we just start developing from childhood.The proof for this statement being that,we do not know what’s fear as a new born.

Well,if that was the case,then why in hell don’t fungi or other microscopic plants develop during their early stages? If you did say that their ancestors did not express any emotions which could be passed on.Then my question to you is,since we all originate from the same single single cell which formed first on the planet,how did we end up being so lucky and the plants not ?

Another such comparison can be made is why did we start looking hair on our body and the other human related apes did not.

Many such questions can be raised.Probably,there already exists an answer to this.But as far as my knowledge which i gained from school is concerned,this is how far i can take it to.

Any comments would be appreciated.