According to the 1861 census a Jabez Barnes was living in the village of Rolvenden with his parents Charles ( a steam engine proprietor) and Anne, his older brother Thomas and his younger sister Sally. The whole family were born in Benenden so this is probably your man. Jabez's age is given as 6 which give birth date of about 1855. Ages on censuses are notoriously inaccurate and often vary from census to census so you need to be aware of this when looking for a birth certificate, but the one you have found in 1855 is almost ceratinly the right one.
Jabez's wife (whose name is given as Elizabeth J in the 1891 census) was born in Tenterden, Kent (a small and very pretty town quite close to Benenden).
Good luck with your researches.