“It still claims that previous studies estimate “Adam” to be 500,000 years old.”
Actually, it states that previous dates ranged from 50,000 to 500,000 years ago. But so what. It has nothing to do with their study.
Previous dates for ancestral Adam ranged from far more recent, just 50,000 years ago, right back to around 500,000 years ago, with some estimates showing major mismatches with the dating of ancestral Eve.
If that's correct, someone needs to explain how the Homo Sapien “Adam” can be dated at 320,000 years in one study, and 500,000 years in a different study.
If there are Homo Sapien fossils that go back 320,000 years, or 500,000 years, I would like to read the research so I can update my knowledge.