Former GM Hanzo main here.
This is intentional. In fact, Hanzo’s projectile has one of the smallest hitboxes in the game – take it from OW developer Geoff Goodman:
The reward for landing an arrow is incredibly high. If Hanzo could easily land arrows, he would be devastatingly broken. A lot of what makes a good Hanzo is not your ability to land arrows on rapidly moving targets. It is your ability to position yourself proactively against unsuspecting targets, thus reducing their effective range of motion and making their movements easier to predict. Your sonic arrow assists with this, but it also gives away your position, so you must time it well and learn when to engage and disengage from fights. The sonic arrow is not just a tool for you, but it is also a tool for your teammates as well, so you need to learn when it is advantageous to use.
You most definitely can keep up in higher ranks with Hanzo. Some of it is mechanical, like learning to flick in mid-range fights, but most of it is positional / game sense.