0 Drops on Act 1

I'm creating a new character and I haven't had any skill gem drops through the entire Act 1 until I killed the Executioner, who gave me a level 5 gem just for the mission. On the map, I don't see any challenges completed, no bosses appear defeated, and it's as if I haven't opened any relevant chests. If I didn't have materials from my other playthroughs, I wouldn't be able to get through Act 1 at all.