The spelling of the Giles/Jiles surname seems to be in some instances a matter of personal choice. The “G” spelling appears to be the more common during the18th and19th centuries.
The most common occurrence seems to be surnames were written incorrectly by accident. People were not as well educated in the past as they are today. Sometimes a name on a document was written as it sounded, or perhaps, it was simply misspelled or misread by accident. In other cases, an individual may have changed the spelling of his/her surname to adopt a different air or perhaps to distance himself/herself with others of the same.
Many different tales have been told (about the surname spellings) and passed down through the years. However entertaining some of the stories may be, none have yet to be proven by me.
I am researching the Giles/Jiles surname and interested in knowing about your Jiles lineage. It would be exciting to find a new family connection. Might you provide a name and date of your earliest known ancestor? My husband is a Jiles descendant and there are records showing his ancestors with both spellings. He had ancestors from NC/SC who were in GA and AL before and after the Civil War.