Why not Jonathan and John are different names, the same as Eliza and Elizabeth in the same family that comes up a lot.
I missed a daughter Sarah bap 13 March 1814 added to previous post.
Son William 1798 marries Sarah Potton 10 July 1817 at Foulness ( I have the children)
Son Nathanial marries Mary Wiskin of Easterwood 25 December 1824 at Rochford witnesses are Mary Simpson and Jacob Stevens
Nathanial dies age 23 buried 16 August 1827 at Rochford address Canewdon.
ESSEX RECORD OFFICE ref 129/13/2 --- Mary Simson + 2 children removed from Rochford to East Bergholt Suffolk dated 1828. I bet this is Nathanial's wife who had to ask for parish relief after he died. The children are William James bap 1 May 1825 and Mary Ann bap 30 August 1827 (of the late Nathanial Simpson and Mary)
Daughter Mary Simpson marries Jacob Stevens 26 December 1824 at Rochford witness Jonathan Simpson and William Topsfield all signed. Note witnesses for brother Nathanial.
Son Henry marries Elizabeth Marvin/Marvyn/Marven, have not found the wedding yet mothers maiden name from youngest children civil registration.
He, Henry also had an illegitimate son Joseph How? bap 23 January 1828 mother Elizabeth How at Foulness.
I'm missing John 1800 and Sarah 1814 either marriages or deaths.