This version of the front roll is performed over as many “soft spots” as possible: Posterior shoulder, hip, leg- as opposed to head, spine, tailbone.
Considered here is the fact that if we fall, it will likely not be on a comfortable, squishy mat, and so minimizing/ mitigating areas of impact is important. The “circle” made with the arms prevents those learning from diving on to their head and/ or shoulder, and provides a simple pathfinder for the roll.
Stay tight, think about propelling yourself “down the hill, not down the stairs”, and once practiced starting on the ground, perform the exact same mechanics from standing, back to stand