When you say the site has misspelt it - do you mean ancestry.com? There are two separate family names "Jelf" and "Jelfs" which almost certainly were originally the same name but which, over centuries, became separate names as did other variations such as Jelfe, Jelfes, Jelff, Jelph etc.
Although the Jelf/Jelfs name appears in Worcestershire, it is also concentrated in Gloucestershire and Somerset which were closer to trade routes owing to the Bristol Channel. That all said, it seems reasonably likely that it is an Anglo-Saxon name originally.