Green’s Dictionary of Slang

(W.I.) ordinary, second-rate, insignificant.

[1968		L. Barrett Rastafarians (1977) 168: Up to the late 1960s, Rastafarians were to be found mostly in areas of the city which used to be called ‘dungle’ – a word which signified ‘dung’ and ‘jungle.’ These were the worst areas of the city, even lower than ghettos].
1995		Francis-Jackson Official Dancehall Dict. 17: Dungle ordinary, of no account: u. yuh a nobody, yuh a dungle.