Just started playing HoMM3 today, I'm new to the series and enjoying it! Something I was wondering about however was the single scenario mode, I started by winning the Dwarven Gold scenario but didn't see any indication in the scenario select screen that the scenario had been cleared after I won. Is there any way to sort scenarios to specifically show scenarios that have or haven't been completed yet, or anything anywhere that indicates that the scenario has been beaten at all? Or will I just have to keep track of what scenarios I've beaten myself?

The only way the game keeps track of finished maps is by the High Score list. But that's limited to ten maps, or so.

Anyway, for Single Player most of the standalone maps coming with the game are inferior to the best user-made maps, of which some are true masterpieces of map making.

Yes, but for someone completely new to the series I suggest playing the original maps first, till you get the hang of it. Some of user-made maps can be super hard if you're not experienced.

Thanks for the heads up and the answer!