Goblins make an excellent starter build, and you've got some good ones.
Your hero is pretty much just another troop. As you level up you'll gain more hero stats. As you finish quest lines you'll unlock classes that give your hero more stats and traits. If your build works without a hero, don't feel guilty. If your build is better with hero, use them, if not, no loss.
Never disenchant troops. When you have over 5 copies you can sacrifice 5 to ascend the troop to the next rarity level, so common becomes rare or an ultra rare becomes epic. This gives the troop more stats and allows you to level it up one more time for more stats. Each ascension for a troop requires more excess troops (5, 10, 25, 50, 100) so it is a long term goal. Don't disenchant any troop until you get it to Mythic rarity and have 4 of them.
A little early advice, unlock as many kingdoms as you can, work through quest lines for free Epic level troop (and for some kingdoms unlock a class), and then use gold to level up the kingdoms. Eventually they'll reach level 10 and give a stat boost to ALL your troops. For example, if you get Adana to level 10 ALL troops get 1 point of extra Armor. And don't be afraid to experiment, there is no penalty for losing really.