I believe Atheism does include the notion of a human soul. Atheist decline the existence of God because there is no actual proof that a god exists. The same can be said for a soul, no one has scientific proof, so it should follow that Atheists also don't believe in a soul.
Atheism is not believing in God. If you don't believe in God, and you can still believe in a soul and you can still believe in the afterlife.
Lots of people believe in these things without have a theistic view. Theism is about God not the afterlife or soul at all.
Atheism is a lack of belief in any god, nothing more. While atheism is correlated with a lack of belief in souls, one is not necessarily a part of the other. I know atheists who believe in souls, and I know atheists who don't. Atheism and the notion of a human soul are completely separate issues.
Although technically the doctrine of atheism should be dealing only with a certain conception of God, it also seems to have to do with not believing in any sort of soul or spirit realm. If someone is not traditionally theistic but does believe in a soul, the best description for the person is spiritual, not atheistic.
No, atheism does not include the notion of a human soul, because atheism by its own premise does not believe that there is a human soul. Atheists believe that humans do not have a soul, and that we are all here by some chance or another. If they reject God, they reject that there is a soul. They believe we are nothing and have no significance other than the here and now.
Atheism does not include the notion of a human soul. An atheist is a person who does not believe in a higher power, a god, a religion, or an afterlife or previous life. Atheists are focused on the present; not the past life or the afterlife. Therefore, atheism does not include the notion of a human soul, because that would imply a belief in anoter form of existence in the afterlife.
Atheism does not rely itself upon believing in the notion of human souls. An atheist does not need to believe in a soul in order to reassure their existence. They probably think that the value of a human being resides in their minds and the actions that they commit daily.