Ah, Google. We love you, but you’re always changing. In 2018, Google has changed again; it’s putting more onus on position zero — as known as a featured snippet — than ever before.
Position 0 is a bit of a misnomer. It’s the top ranking in the SERPs that’s above position 1.
Why is it above position 1? Because Google has deemed that it’s got the best answer to a particular search query.