I search the ROOTSIRELAND.IE database. It has abt 20M B/M/D records and covers most of Ireland.
For David Jarvis B 1863 +/- 5 yrs, somewhere in Ireland, with a father forenamed Alex(ander) and mother named J(anet), I found 0 records. Since this is the most likely record to have survived, I didn't search for the others.
For Al(exander) Jarvis M 1854 +/- 3 yrs, somewhere in Ireland with a spouse recorded as Jane, I found 1 record in Co. Derry. A view of the detailed record (for a small fee) may give you more information.
The Jarvis surname is likely protestant. Protestant records are far less likely to have survived.
Suggest you visit this database and register (free). It will notify you as other records are added to it.