Some of my most vivid memories from when I was Zoe’s age are of my dad reading L. Frank Baum’s Oz books to me, particularly with the John R. Neill illustrations (I really wish I could find an online scan of the dreaded Scoodlers to link to).
As for letters and numbers and basic words I spent countless hours as a kid poring over some giant Richard Scarry collections we had. Since I’m not sure of the titles, it’s difficult to find these exact books online, as Scarry has published hundreds of books in various alternate versions and collections. This is the closest thing I can find to what I remember. But from what I’ve seen, any Scarry is good Scarry.