The same man also appears in 1881 and 1891 still in Cornwall with the family you found in 1901. The apparently oldest child Clara was 4 in 1881, so if you can find the date of his marriage to Jane, perhaps on freebmd, you will be able to send for the marriage certificate (£7 ) and that should give the name of his father, which would prove or disprove the connection for you. Good luck
Susan