The fact that the "soul" is not unique to Judaism does not prove this idea fake. If anything, it proves our intrinsic human belief in the notion of souls. The idea of a soul is seen in many current world religions, and many pagan religions of the past. The idea of a soul is even seen in remote, isolated areas of the world.
Of course the ideas of the Abrahamic faiths aren't unique, a religion that promotes ideals contrary to current belief systems would never make it. Judaism, Christianity and Islam were not the only religions to come out of the Middle East, they were simply the ones that caught on and survived.
Never look at whether or not a religion is "true or fake." Instead, look at how that religion affects people who follow it and how it affects society. All religions have truth to them to the people that follow them.