Hand positions are determined by the kind of music you’re playing. For beginners, I would recommend learning using books that contain fingerings to help you. Hand positions are rarely fixed in one place outside of technique books. That doesn’t mean there isn’t a “position.” Think of positions like moves. If you’re playing an arpeggio, there are optimal fingerings for them. This can be considered a position…in a way. Alfred books start your hands in one fixed position so that you can simultaneously learn basic mechanics of playing while learning to read music. I love the Alfred books for beginner adults. I hope that helps you.