What is the reason for the arrangement of “qanoot” (devotional standing), then prostration, then bowing in the verse, “O Mary, devote yourself with obedience to your Lord, and prostrate, and bow with those who bow,” and was prayer obligatory before Islam?

The noble verse, "O you who have believed, bow and prostrate and worship your Lord and do good that you may succeed," includes mention of al-qunūt (constant obedience), then prostration (which is more specific), then bowing (which is even more specific). And the conjunction "waw" (and) does not imply temporal order.