Isaac born 1897/98 is unlikely to be Nicholas' son, some 30 years after the marriage of the parents.
Freeholder Records show a Nicholas McCann in 1830 in Ballyhanon (sic), Co. Armagh. There is also a Henry McCann noted in the same place at the same time.
This might be Nicholas Sr's death:
Name: Nicholas McCann
Estimated birth year: abt 1795
Date of Registration: 1869
Death Age: 74
Registration district: Lurgan
Volume: 6
Page: 571
FHL Film Number: 101584
Griffiths Valuation (taken about 1864 in Co. Armagh) show the two possibilities (likely father and son):
Occupier: Nicholas M'Cann
Lessor: Stewart Blacker
County: Armagh
Barony: Oneilland, East
Parish: Seagoe
Townland: Ballyhannon
OS Page Numbers: 10
Occupier: Nicholas M'Cann
Lessor: Anne Jennett
County: Armagh
Barony: Oneilland, East
Parish: Seagoe
Townland: Breagh
OS Page Numbers: 10
Also a sublet of note:
Occupier: John M'Cann
Lessor: Nicholas M'Cann
County: Armagh
Barony: Oneilland, East
Parish: Seagoe
Townland: Ballyhannon
OS Page Numbers: 10
Henry also appears in the Revision Books when his land was taken over by Simon Somerville in the first revision in 1875. There are numerous revisions to the McCann properties in Ballyhannon that are too difficult to list here, so suggest you have a look for yourself at the PRONI website.