The overwhelming consistency among flood legends found in distant parts of the globe indicates they were derived from the same origin (the Bible's record),
or.. presumably, equally likely that the bible's record was derived from some other or some conglomeration of the other flood legends.
A local flood at these times may well have given the impression that the whole world was flooded.
It would be interesting to look at the geographical locations of all these flood originators and see if they are flood prone areas.
but oral transcription has changed the details through time.
but wait! isn't the god inspired truth meant to be infallible? other wise what other 'details' have changed through time and transcription?