Head coach Hugo Broos on Monday announced that Williams would captain Bafana with Percy Tau as vice-captain.
Heredia, who has worked with shot-stoppers such as Hans Vonk, Andre Arendse, and Brian Baloyi, has now backed Williams as skipper.
"To be honest, he is a quality goalkeeper in the PSL," Heredia tells snl24.com/kickoff.
"But with Bafana Bafana, he had several opportunities and never really had a tremendous impact as with the likes of Calvin Marlin, Andre Arendse, Brian Baloyi or Moeneeb Josephs.
"During their careers, they were the out-and-out number ones, like Itumeleng Khune was too.
"But if you look around, Ronwen is the one and the only. Tell me, which other goalkeeper makes a difference at that young age over the years?
"I think Ronwen Williams is the one. He's a goalkeeper with experience and the only one thinkable.
"If you look at the names in the squad, Ronwen and Percy Tau probably are the more experienced ones."
Heredia added that Wiliiams' experience as a club captain would also hold him in good stead.
"Ronwen has captained SuperSport United for many years now, and he has personality as I know him personally," Heredia added.
"He knows what he wants, and he will represent the rest of the team. He is not scared to talk. In a game-like situation as a captain, you have to do what any captain can do.
"But it's not only during the game, but it's also about the team, the leadership."
Bafana Bafana get their 2022 World Cup qualifying campaign under way against Zimbabwe on Friday.