If I understand you correctly the drivers door lock switch will unlock the doors but will not lock them? You are wondering what the switch on the lock cylinder is for? What happens when you press the last 2 buttons on the keypad at the same time? Does the doors lock then?
Will the passenger door lock switch lock the drivers side?
Sounds like you have a wiring problem then. Check the PK/BK wire at the switch 1st it should have power when lock is pressed then make sure you have it at the actuator.The PK/O will be ground when lock is pressed. They will swap when you go to unlock.
When you input your keyless entry code and the press the 3/4 button will the other doors unlock then?
The switch on the door lock cylinder is just an alarm disarm switch, this is all it does.
Here are the schematics for the locks. Maybe this will help you pin-point the concern.
It looks as if the switch just grounds the coil side of the relays.Then the actuator is controlled by the relays.The relays are located in the left quarter panel. You should be able to access then thru the cup holder. see the 1st pic F6 location relay box no.4.
Can you find these wires inside the pillar behind the kick panel? See if you have it there.
I suspect the PK/O or RD/O is broken somewhere.
Try running a jumper wire from the actuator to the wire in the kick panel momentarily and see if that makes it work.