I posted just now on another thread the following, but I should have posted it in this one instead. See below:
So basically, no gothic earth character can start with common?
Practically speaking, yes, they can't. But technically the answer could be maybe. Though very few do, demihumans exist in Gothic Earth after having been sucked into it via the Shadow Plane, similar to how the mists grab people for the Demiplane of Dread. These demihumans can come from any D&D world, such as Faerun. From the PoTM forum's Gothic Earth resource thread:
These beings, now trapped on the Gothic Earth, are known as the Shadowkind. ... A character who begins play as a newly arrived Shadowkind knows one or more languages, most of which are not spoken on Earth. Such languages include Celestial, Draconic, Elven, and Goblin. However, they all share a common language (called Common) that has striking parallels to the predominant language spoken in the area where they arrived. Shadowkind characters born and raised in our world gain languages as human characters do. In addition to one or more local languages, they may know one or more languages of Shadow (taught to them by their parents and elders)."
So demihumans and those with partial demihuman ancestry in Gothic Earth can know languages spoken in other planes, including D&D Common. Furthermore, it is also possible for full humans of Gothic Earth to have learned these languages too.
Natives of the Gothic Earth — human and Shadowkind alike — can learn new Shadow languages only after they are exposed to them; they can’t master them spontaneously. To learn Draconic, for example, a character must spend time with creatures that speak Draconic or find someone with access to the written language (Draconic “books on tape” or ancient texts written using the Draconic alphabet, for example). Certain Shadowkind know languages commonly spoken among members of their species, and all characters may study and learn new Shadow languages...
I would guess, however, that it is far more likely for a Gothic Earth human to arrive through the Mist knowing Elven or some other racial language rather than Common, which is not really part of any demihuman's heritage. It is unlikely that passing on Common to descendants and allies on Gothic Earth would have been a high priority among Shadowkind, whereas a racial language would be a matter of pride.
EDIT: It is also arguable that the knowledge of D&D Common that demihumans possessed has been warped by coming to Gothic Earth, as it says that the language resembles the tongue of any nations they find themselves in. So, honestly, already knowing Common seems to not be an option for Gothic Earth characters, but knowing racial tongues such Elven, Dwarven, etc. would be possible.
http://www.nwnravenloft.com/forum/index.php?topic=21168.0