Knock Yourself Out (and Don’t Knock a Creature Out)

As the spell says emphasis mine:

Choose one object weighing 1 to 5 pounds within range that isn’t being worn or carried. The object flies in a straight line up to 90 feet in a direction you choose before falling to the ground, stopping early if it impacts against a solid surface. If the object would strike a creature, that creature must make a Dexterity saving throw.

The object is the target and the spell launches it up to 90 feet. It goes in “a direction you choose”. You choose whether to launch it in the direction of one or, ideally, more creatures (in a line up it would go through each one until one failed the saving throw). It only takes damage and possibly breaks by the terms of the spell (rather than a DM ruling on falling to the ground or what have you), if it hits something (creature, door, whatever).

Note that the “up to” implies you also presumably choose the distance it goes (or maybe not, for a thorough discussion see this question). In any case, it helpful for snatching an object in range and stopping it wherever you want. Catapult is a utility as well as an attack spell. This is, in fact, one of the principle (mechanical) reasons one might choose this “might hit and requires an object” spell over something like the “guaranteed to hit for an average of three less damage” Magic Missile (I believe the other popular reason is that you can fire a flask of acid or such, potentially for more damage on a hit).

In any case, if you ever have that occasion when the McGuffin is on a pedestal next to the big bad rather than held, you’ll have a lot of fun with this spell. It’s also, naturally, what a stylish wizard would use to throw their grappling hook.