The answer to this question can be found near the story's conclusion. The "ancient" village person that this question is asking about is Peter Vanderdonk.

Peter was the most ancient inhabitant of the village, and well versed in all the wonderful events and traditions of the neighborhood.

Peter's role in the story is small, but it is important. Rip has just come back from his extended sleep; however, nobody believes his story. They think it is the ramblings and fantasy of an old man. Peter is a wise and respected ancestor of an important historian in the town, and Peter says that it is a fact that the Kaatskill mountains had always been haunted by strange beings. Hendrick Hudson and his crew are such beings, and even Peter's own father claimed to have seen them playing nine-pins. With Peter's testimony of support for Rip's story, Rip is now believed. He lives out the rest of his days doing what he always did best—telling kids stories.