Finally, it's late and I'm tired, which is why I ended up failing to suggest a second halfling move or devise a full alternate human thief move. However, I do want to mention that I'm planning to add half-orcs to my campaign setting, so I need to come up with a few half-orc moves.
In first edition AD&D, half-orcs could be clerics, fighters, or thieves (or assassins). I figure I'll definitely want moves for half-orc fighters and thieves, but I don't know if I'll give them clerics too; I probably will, given some of the setting details I've come up with.
Anyhow, I figure I'll give the half-orc fighter the move that halfling fighters currently have, as it makes more sense to me.
Fighter—Half-Orc: You're tough enough to shrug off some damage. You have +1 Armor.
Because the original AD&D half-orc could advance unlimited levels only as an assassin, it seems like a good idea to give the half-orc thief a move that reflects that origin. Maybe something like this.
Thief—Half-Orc: You have a sharp eye for your victim's weak points. Your attacks always deal +Piercing 1.