High fidelity fitness tracking for workouts and data collection of your own personal health.
There was all that stuff about "connecting" (where you could send doodles and heartbeats to your Apple Watch wearing friends) and they made a big deal about watch apps and notification management. And of course the "luxury watch" aspect (gold watches that go out of date in a couple of years - sheesh).
It's only after a couple of iterations that Apple doubled down on the fitness side of things.