Your child is learning to read, and you want to know what to actually hand them next. Start at the top and work down. Each book asks your child to carry a little more of the reading themselves — from a story you read aloud while they follow, through books you trade off page by page, to a whole book they finish on their own.
What rises across these books is how much of the reading your child does themselves. At the top, you're still doing most of the reading aloud while they follow the rhythm and chime in. In the middle, you trade off — you read a page, they read a page, you take the hard words. By the bottom, they're finishing a whole small book on their own. That's the whole climb, and it's worth naming out loud as they go: this used to be my job, and now it's yours. Don't rush it — each rung should feel easy before the next.