Borom Sarret

Over one day in Dakar, a poor cart driver carries passengers who often cannot pay, among them a father with his dead child who is refused entry to the cemetery for lack of the right papers. Later he agrees to drive a well-dressed man into the city's French quarter, where carts are banned; a policeman stops him and his cart is confiscated, while the passenger leaves without paying. He returns home with only his horse, and his wife hands him their baby and goes out, saying she will make sure they eat. The first film over which Ousmane Sembène had full control, it is often called the first film made in Africa by an African, a claim Wikipedia notes is disputed, and it was shown in Cannes Classics in 2013.

Note on sources: Wikipedia gives the running time as 18 minutes, the Festival de Cannes website as 22 minutes, and Dennis Schwartz as 20 minutes.