Actually I think it's an old English name--I have some Bigge ancestors and they all come from England. They lived in what is called the "Weald" of Kent, in towns named Benenden and Tenterden and other villages in the area. This line can be traced way back into the 15th century.
It's entirely possible that "Bigge" comes from an old Saxon name, so it would be "German" in that sense--but in my family it is strictly English!!