Answet: all, except ‘an’ that does not exist, are prepositions. One of them showing a movement towards (a = accusative) and one a location of origin (de = dative). Being of origin, it may have some genitive use (belonging to). « Je vais au bal » (I’m going to the dance; au is the contraction of a and le, gender male with determined article). « Je viens de la riviere » (I come from the river; du is the contraction of de and le, gender male with determined article). In genitive use: Je l’ai pris du musée. (I’ve taken it from the museum). In cases of personal belonging is used the preposition ‘a’: La montre est a mon pere (the watch belongs to my father), which, meaning towards may though still have some genitive use (contrary to Spanish).
There are other uses, mostly in verbal turns, but it should be possible to derive them from the before mentioned.