If memory serves, they're from various stock cartoon sound effect packs and sample CD tracks. Some of them are by Mel Blanc but there wouldn't be a single voice actor.
SM64 is hardly the first time Mario was voiced, though! Earlier portrayals like Lou Albano's are still fairly popular.
But i do wonder if the stock sound effects are the earliest by date of recording, making one of those voice actors the earliest chronologically—or is that what you meant in the first place?