The title is accurate. The article states explicitly that 3000 years ago the common ancestor of all of humanity existed. It's just that 3000 years ago wasn't the point where one and only one common ancestor existed; some 80% of the population may have carried that distinction.
> The title is accurate. The article states explicitly that 3000 years ago the common ancestor of all of humanity existed.
The title -- "In 3000 years someone alive today will be the common ancestor of all humanity" -- is not accurate. There was no single "common ancestor", because modern humans owe their genetic inheritance to multiple sources. This will be true in the future as well.
I'm not sure I understand the relevance of your point. If you're saying that there is no single common ancestor, but multiple common ancestors at the timespan of 3000 years, then yes that is true. But that doesn't invalidate the fact that any of them is the (perhaps better stated as "a") common ancestor.
