Many immigrants deliberately Anglicized or changed their surnames upon arrival in the New World, so that Mlynar became Miller, Zimmerman became Carpenter, and Schwarz became Black. Hence, regardless of the current spelling of your surname, the spelling and pronunciation of your surname has evolved over the centuries. In many cases, the current generation may be aware of the change. However, in many cases the change of the surname occurred so long ago that they are not aware of the original spelling and pronunciation of their surname. To the trained genealogist, the change or evolution of most surnames is obvious and very interesting, particularly to the bearer of that surname.
Many German names have their roots in the Germanic middle ages.
All social classes and demographic strata aided in the development of names. The earliest are the names derived from the place of dwelling and the location of the homestead. If a person or family migrated from one place to another, they were identified by the place they came from. The largest group and the most easily recognizable names are those derived from the vocation or profession of the first bearer. They tell you what the first bearer did for a living.