If your ancestors were from a small town and you can’t find their parents, perhaps they’re hiding under another name.
There wasn’t a great influx of new people in a small town, so don’t automatically assume that people came from elsewhere if you can’t find them. They could be hiding under a different farm name, or their last name could be a patronymic referring to the first name rather than the last name of the father. Or maybe they were the first in their family to use that particular name and their parents used different names.
By expanding your research and studying baptismal witnesses, neighbors, and naming patterns, you may identify candidates for the parents. Court and notarial records may provide additional evidence.