-FRIDAY, SEPTEMBER 15, 2000- PARIS--Thousands of years before the Bateaux Mouches began plying the Seine with sightseers, Neolithic Parisians cruised the river in dugout canoes, fishing and trading with their neighbors upstream. Three 6,000-year-old canoes, unveiled on Thursday, suggest human settlements were set up at the location of present-day Paris, up to 1,500 years earlier than what had been believed. The 20-foot canoes, each hewn from a single oak log, will be the centerpiece of a new wing of the Carnavalet Museum scheduled to open later this year.  The earliest of the dugouts, which experts say dates to 4,500 B.C., were unearthed along with thousands of artifacts by French archaeologists in 1990, during a major urban renual project on the banks of the Seine at Bercy, in southeastern Paris.