I think I have a likely John
bapt German 17561205 s/o Patk Cubbon + Averick Shimmin - averick d 1762 - will husb patrick;1774 john & thos cubbon ack from fa patrick;sister ann dead;ch ua supv phinlo shimmin, henry quilliam husb of margt quilliam als shimmin,nichs shimmin
Patk then remarried to ann crain
she d 1780 will - d 10 [] 1780;will torn;ch edmund + ann (ua);uncles wm + nich craine + silvester cottier h/o jane craine guardians;husb wm
Patk then remarried to Ann Craig
and died 1785 - will d 6 sep;3 sons jon thos + eoman ? [edmund] ;dau ann;son pat;wife ann;[Pat, John + thos are from 1st marriage to averick shimmin - note wife ann craig is 3rd wife, 2nd is ann craine]
(will summaries on Manxnotebook but your query made me reconsider and determine tge 3 marriages
Thus this John is a likely emigrant - no property to inherit - both parents dead + the stepmother who brought him up also dead