Unable to find simple outdoor run option on Apple Watch Ultra 2

Go to the Workout app on your watch. If you don't see "Outdoor Run", scroll to the bottom and and tap "Add Workout." If you see anything other than "Open", tap on the three dots and scroll till you see it and select it. If you use that, it will track your time and distance until you stop it. It should default to that the next time you run. In addition to "Open," you can chose time, distance, pacer, calories

You can also create a custom workout:

Create a custom workout on Apple Watch - Apple Support

If I were you, I'd consider deleting any custom workouts you may have inadvertently created (they will be purple as opposed the default green workouts). That way, you can start over again.