What defines a human? Anyone's ability to read this article and think about it. Human imagination is what seperates us from the rest of the animals, atleast in the cognitive part. Early human societies have always been characterized by beliefs in common imaginery creations like religions, nations and the monetary system. This has pretty much been happening throughout the human history with various events proving the inevitable direction for any major goal accomplishment-cooperation. People have been cooperating, shaping goverments, corporations, communities, etc because its simply easier to work together in order to achieve what one cannot do on his own.

So as much as we want to deny it, common myths and fantasies float around our everyday life like ducks in a pool. So why haven't we been able to get rid of them or atleast minimize the inevitable drawbacks that they come with? (fanatism,genocides, etc)

Its because of the simple fact that those fantasies are connected with the material world around us and most importantly with the people we care about, blending the cognitive with the emotional part. So its not so simple to just reject any kind of bullshit you have been told since you were born because those things are the ones (atleast in a small percentage) that defined you in the first place!

And you cannot consciously delete memories/experiences just because you choose too.
So in the end I think that a human is defined by his evolved cognition but at the same time caged by it in a subconscious way, making us quite an ironic existence in this universe.