Human life did originate from Africa, so in that sense we are all from Africa. That is where Neanderthals evolved into Homosapians, there is no evidence of them living in any other continent. So in that sense we are all Africans, or from Africa.
African Americans were not born in Africa for quite a few generations now, yet we still call them African. African is not synonymous with black.
Regardless, people are reading too much into a T-shirt that's meant to be a quick catchphrase.
Lololololololololol lo lo l l l l l l l l o l o l o l o l o l o l o l o l o l o l o l o l o l o l o l o l o l o l o l o l
It used to be thought that all people, in evolutionary theory, came from Africa. However, this has been debunked as signs of civilization including literacy and documentation are being found all over the world including the United States that date back way before even the popular idea of human beginnings 10,000 years ago. In fact, some writings have been found that date so far back even carbon dating is unable to identify a timeline.
A lot of the comments that jakscrow has posted talks about remembering roots and he discusses that we all have African genetics. If 'having African genetics' is your definition of African, then undoubtedly any person who believes in science and that we indeed migrated from Africa will say yes. It's a scientific fact that cannot be disputed unless you truly believe in the whole Eden and Earth was formed 6000 years ago thing. And if that happens, you're literally looking at a 'does God exist or not' kind of debate. So please, define your terms, or this isn't going to be a debate at all -- it'll just be a clash of religious and scientific views.
Just because that is where the first humans originated and evolved does not mean that we are all still African. Our ancestors from 400 million years ago were fish. Does that mean we're fish today? No, nobody would argue that. So what sense does it make to say that we're all Africans just because of who we were 2,000,000 years ago?
Not that there is anything wrong with being so, just to point a fact. Yes, according to research, mankind did come from what would some day become known as Africa. Seeing that it was not called Africa at the time or for thousands of years means that they did not come from Africa so they were not African. Not sure what the continent was called back then, or even if it had a name but clearly it was not called Africa at the time my ancient ancestors migrated north to what would be called Europe.