Are humans inhuman?(The Lord of the flies)

There is one thing that I do not understand in reference to 'The Lord of the flies', how can the children simply kill another one of their own without hesitation and even take pleasure in doing it. It shows the true nature of humans: cold-blooded and cruel,extremely cruel.
Ask this question "Why do humans like to abuse defenceless animals and take pleasure in doing it?", why doesn`t the newspaper once read ' Tiger mauls its keeper and smiles'.
Even when animals kill other animals, they do not 'smile in glee as they devour their prey'. They do it for one reason-survival. However, humans simply kill others for no particular reason because they are just bloodthirsty. One examples are the children in the story: At such a young age, they know how to kill one another and do not feel remorse from it. Yes, there was nobody to correct their wrongs at that time, but isn't it common sense to not kill another one of our own?
It is similar to a kidnapper killing his hostage after he got the ransom. Why does he even do that? The hostage is defenceless and poses no threat, the kidnapper got what he wanted and he has no particular reason for killing him. The kidnapper might as well say "Give me a ransom of one million dollars AND I will kill him".
Furthermore, another question I would ask is why are humans so superstitious that they are willing to kill one of their own kind for silly and non-proven rituals? Another example I got was from the story I learnt last year, "The lottery"
Are humans so eager to see someone else scream or to experience pain? If they like it so much, why don`t they do it to themselves? Afterall, they will get a `first class` experience.
Humans are even willing to kill their loved ones for silly reasons such as money problems, rituals, etc. These actions are totally pointless and the worst part is ,most of the time the culprit does not feel remorseful and treated it as of no significance.
I admit, when I was young I used to get a kick out of stamping on frogs.
Why does this habit come naturally for humans and not for other, less intelligent animals? Are we really inferior to them?
What is the point of being the most intelligent animal if we are also the most cruel animals because of that?
Another thing is, whenever you bring up this topic, it will cause an uproar. That is because of humans` pride, they just would not admit they are heartless and cruel. A good example is when 'The Lottery' first appeared in The New Yorker magazine.
The scary part? These 'trends' tend to come naturally in our life. To all abusers of any kind out there, please change so that humans can clear this image of ourselves.