If you look at that mess in the black plastic box, there were several people that got it right.
#1) Put a jumper where Klattu says to; between the incoming Black limne and the lug to the left. This makes all connections 120V that the breakers connect to.
#2) Buy a grounding bar and add it somewhere at the bottom of the box, connected to the heavy ground wire and to all other ground wires, the green wire coming in and the other green wires that go to other things like the electric water heater.
#3) connect the white neutral wire to the top left neutral bar and all the other neutral wires.
The box I bought for a replacement was a steel box with the exact interior components as the plastic box (I mean picture perfect twin on the whole thing).
Once I got the new box and disassembled it next to the plastic box I also disassembled the mystery solved itself.
It was easy to see how the electrician separated the circuits so he had 3 120V breaklers and 1-220V breaker in the same box.
As for the 30 Amp main breaker its just added to the left of the new box with jumpers going to the new box.