American Girl dolls were initially produced for Pleasant Company by the German doll company, Goetz.
So there are Goetz 18″ dolls that have the same body as American Girls.
There are even some (older ones) that share the same face mold, although those Goetz dolls with the AG classic mold that I´ve seen on ebay so far have a vinyl body or a different stuffed fabric one.
Here´s some examples (all pictures taken from closed ebay auctions and featured here for documentary reasons only):
This Samantha lookalike is marked “Götz-Puppe” in the back of her neck and has a vinyl body.
And here´s a boy – from the auction description, he´s called “Justin”.
Another boy. According to the auction description, he is called “Max”.
This is “Silke”, a 20″ collectible doll made and signed by Marianne Goetz.
The similarity in style of the face sculpts, also shared by some other dolls made by the same sculptor, makes it likely to me that Marianne Goetz was the doll artist who also sculpted what would become the American Girl classic mold.