This might be more of a question for /r/askscience, as it will reach into the fields of human paleontology and cladistic analysis of "last common ancestors".

It is believed so. According to genetic research, it appears that every single person's mother's mother's mother's mother's... etc, etc... mother, was a particular woman known to scientists as Mitochondrial Eve* (named obviously after the Biblical Eve). She's theorised to live between 99,000-200,000 years ago, probably in central East Africa.

*The researchers who discovered this didn't call her Eve, but it's the name that caught on. It has awkward connotations, because people may assume that she was the first human, or the only human woman at the time. In fact, she's simply a woman we are all descended from. Presumably, there were other women at the time, but their families died out.

It's also likely that we have a more recent common ancestor, it's just that Mitochondrial Eve is the only common ancestor that can be shown genetically. Remember that as you go back in generations, each person has many, many descendants. My grandma has 8 descendants alive today, her mother had about 20, her mother had something like 35, and so on. So someone living 10000 years ago probably has millions upon millions of descendents alive today. Thus, a common ancestor more recent than Mitochondrial Eve is statistically likely, even if it can't be proven.