This is veering very much into off topic territory.
Book and recordings either manage to track down the original voices or they don't. Don't, usually in a case of movies where they'd have to pay celebrities, or in the case of the project just being a cheap merchandising grab. Then there's recordings made in the 60's, where voice actors were actually under contract to certain record labels and couldn't reprise their roles. And for the sake of conversation, the two times I was impressed by them getting the original cast for book and recordings were the rare as heck Legend of Zelda and Dennis the Menace ones using the DIC cast of both shows when they didn't need to. Both can be found on Youtube by looking hard enough.
Anyway, near as I can tell, the first Sesame Book and Recordings used a narrator to cover at least some of the characters to some extent. Never was a fan of that.