https://www.bdm.nsw.gov.au/Pages/family-history-research/family-history-research-nsw.aspx Some observations:
The first use of the surname KINGMAN on NSW BDM online indexes: (I cannot see any sign of Benjamin KINGMAN, nor any connection between any of the following and Benjamin KINGMAN, last sighted in NSW official records in 1805).
Death of Maggie KINGMAN in 1884, she was aged 30, she died at Camperdown and her death was registered in the Newtown district (Camperdown is an inner Sydney suburb).
Birth of twins for Albert C and Annie KINGMAN in 1883, registered Glebe district (inner Sydney suburb).
Marriage of Albert C KINGMAN and Annie HARRIS registered in 1883, Redfern district (inner Sydney suburb)
Albert C KINGMAN’s death registered in 1935, he was aged 79 years, he died at Woollahra (inner Sydney suburb).
The marriage KINGMAN=HARRIS … May 12, 1883 announced in the SMH 19 May 1883
https://trove.nla.gov.au/newspaper/article/28374750 The death of Maggie KINGMAN, beloved wife of Charles
https://trove.nla.gov.au/newspaper/article/163270748 Sydney Mail 27 Sept 1884
Sadly, an infant death, Arnold aged 13 months, Westmoreland St, Forest Lodge… Cutting in Australian Star, 22 Feb 1892.
https://trove.nla.gov.au/newspaper/article/163270748 I can see online images that include Benjamin KINGMAN who was sentenced along with the following who all came on that same voyage in 1804:
Henry MURRAY
John GUEGEN (JM not sure of that surname spelling
)
George MITCHELL
John Cook FANCUT
I also tried :
https://www.records.nsw.gov.au/archives/collections-and-research/guides-and-indexes/indexes-a-z and
https://www.records.nsw.gov.au/archives/collections-and-researchJM