I seriously doubt you are missing any civilizations. Cultures and civilizations are not the same thing. There are more cultures than civs.
No civilization has a UU or UB. They come with cultures which you get by building wonders which have a variety of requirements like one or more specific resources in the city's BFC (which must be improved and hooked up so you get the resource).
You may be the playing as, for example, the German Empire but you are not culturally German until you get the German culture wonder built. Until you are culturally German you can not build the German UU/UB/Hero type stuff. EVen though you are called the "German Empire" you may never become culturally German, but you might end up with French culture because of the things available on the part of the map you are on.
In essence, your civilization only provides a name for the civilizations, and a matching leader, a list of names that will be used by your cities, a flag, the civilization's color(s) (as show on the map), and some style type things (appearance of some units, the language they speak when selected, that sort of thing). This makes it easy to remember who is who. Each civilization has a regional type culture (European, African, etc.) which acts as a prereq in determining which culture wonders you can build (you need the European culture to be able to build the Roman culture wonder and get the Roman culture). There may be a more detailed list of exactly what the initially selected civilization gives you somewhere, but this should be most of it.
An explanation of this really should be in the FAQ. It comes up more often than at least half the things in it, possibly any of them except perhaps the first one.