I am a long time Scottish Kincaid researcher. Sorry I did not note your post earlier.
John George Kincaid, the shipbuilder, was the son of Thomas Kincaid and Ann Henderson, and was baptized in East Parish, Greenock on 26 October 1840.
Thomas Kincaid, was the son of Alexander Kincaid and Jean Clark, and was baptized in Falkirk Parish, Stirling on 2 October 1796. See GROS, West District of Greenock, Renfrew County, 564/03 0167. p. 56, no. 167 for proof of these connections.
The family grave plot in Falkirk church yard records that Alex Kincaid, second son of Thos Kincaid and Eliz Chislie, died on 17 February 1854 at the age of 91 and that his wife, Jean Clark, died on 28 October 1840 at the age of 76 [Mitchell, John Fowler. Monumental inscriptions (pre 1855) in East Stirlingshire. Edinburgh: Scottish Genealogy Society, 1972].
Alexander, son of Thomas Kincaid and Elizabeth Cheesly, was baptized in Falkirk Parish, Stirling on 13 May 1764 in Falkirk, Stirling. Alexander's brother, John, was the father of the famous Sir John Kincaid of the Rifle Brigade (Napolean Wars).
As to the ancestry of Thomas Kincaid (m. Elizabeth Chislie) I need further documentation to cement the link, but I believe that he was the Thomas, son of John Kincaid and Jean Kincaid, who was baptized in Falkirk Parish, Stirling on 17 May 1730. These are the Kincaids of Grange. John Kincaid (m. Jean Kincaid) was the son of John Kincaid (m. Margaret Lorn) who was the son of John Kincaid (m. Jean Livingstone) of Abbotsgrange. John, son of John Kincaid and Jean Livingstone, was baptized in Falkirk Parish on 19 February 1670. I also need further information to cement the links further back than this. However, the ancestor was certainly David Kincaid who married Elizabeth Livingstone and flourished in the mid 1500s. In the line was at least David's son John (m. Grissel Salmond), grandson James, and great grandson John who seems to old to be the John who married Jean Livingstone; so there may be another John in between.
This should give you something to digest.
Peter