An Atheist said that they believed that humans put personhood characteristics onto God. Humans couldn't do that unless they had personhood characteristics, hence the Atheist admitted that they accepted that humans have personhood characteristics.
The Atheist says that there is no God yet humans are people and have personhood. Those two contradict each other because in the Atheist worldview there is no foundation for personhood, there is just matter.
There is nothing about the atheistic worldview that would deny the existence of personhood. Let's look up a few defintions of "person" from dictionary.com:
1. a human being, whether man, woman, or child:
The table seats four persons.
2. a human being as distinguished from an animal or a thing.
3. Sociology . an individual human being, esp. with reference to his or her social relationships and behavioral patterns as conditioned by the culture.
4. Philosophy . a self-conscious or rational being.
5. the actual self or individual personality of a human being:
You ought not to generalize, but to consider the person you are dealing with.
6. Law. a human being (natural person) or a group of human beings, a corporation, a partnership, an estate, or other legal entity (artificial person or juristic person) recognized by law as having rights and duties.
I agree with all of those definitions of "person", and not one of them is compromised by my lack of belief in a god. Note in particular the sociology, philosophy, and law defintions.
You seem to be under the illusion that if one believes that only matter exists, then it must follow that everything reacts as if it were a rock. Conciousness and self-awareness are commonly described as emergent properties of a physical, material thing: the brain. Matter is so much more versatile than simple, passive rockdom.