Yeah I’m American and we had mostly Scholastic book fairs and the school library to count on for books. Animorphs, being published under them, was heavily advertised at the fairs.
Considering myself to be an “advanced” reader I’d stick to the young adult books, but mostly sci-fi (Dune) and fantasy (Dhampir). For 5th or 6th grade me, though, Animorphs was engaging enough until a new book came out and was constantly checked out at the library.