More literally translated as 'vindicator' and not understood to refer to God, and since there's no concept of Jesus in the Tanakh, it's not a reference to Jesus either. It means someone who will vindicate Job in his lifetime and put an end to the appalling nature of his life.
(I find the morality of the Job story entirely revolting, indefensible.)
There are multiple interpretations for most key words in the bible. You can take your
pick, as the Jews love to do. But the context is of an existing figure who will one day
stand upon the earth, someone who Job foresaw in his suffering.
David spoke in the same way - seeing the same figure in his suffering.
Re the 'appalling nature of his life'
Solomon never suffered like his father, King David, and there's no humility, contrition,
empathy, love etc in Solomon's words. A life of luxury made this man darker in his
outlook. His last book, Ecclesiastes, is rather dark and depressing reading. And no
vision in Solomon of the Messiah.
So there's something to be said for the 'appalling' lives many of the bible's saints lived.
avenger (13), bought back (1), buy back (1), claim (1), close relative (3), closest relative (3),
closest relatives (1), ever wish to redeem (2), kinsman (2), redeem (22), redeemed (25),
redeemer (1), Redeemer (18), redeems (1), relative (2), relatives (1), rescue (1), wishes to
redeem (1)