And the article speculates that they are revolutionary war soldiers who died in 1777. So 70ish years after the house was built. Why would someone dig up their basement to bury ward dead? Answer: they wouldn’t. So the 1777 theory doesn’t hold much water.
From reading another article; it might be that the burial site was outside of the original home, which was very small. There were later additions and renovations where foundations & rooms were built over the unknown/unmarked grave-site.