How to fix car brake jam due to not used in rainy days & humid environment.

I saw what you replaced, didn't see any testing? What testing have you done? Make sure battery has a full charge?
When the problem is ongoing, have a helper crank it, while you check for spark at the plugs. If spark everywhere, use a gage and check proper fuel pressure. Also, check fuel injector pulse. Any applicable trouble codes?
If you have the spider fuel system, that system is noted for problems.

Makes perfect sense! The rotors are made of regular steel. Usually in rainy areas they will rust if not used. I live in Oregon and my rotors get very squeely if I don't drive that vehicle for a while. There are varying degrees of fixes based on just how bad the rotors are rusted. Usually, "turning" the rotors and cleaning or replacing the pads will do the trick.
Good luck

Actually, you will have to have the throttle body bore cleaned physically. There will be carbon build up preventing the TB plate from closing completely. Lucas gas additive used twice a year will prevent this from reoccurring. Mercury Marine gas additive is GREAT as well!

The bulb, or the full assembly?

If just the bulb, it's easy. Lower the tailgate. On the inside you will see the 2 hex screws that hold the assembly in place. Remove those carefully so you don't lose the nut inside the body, and carefully pull the assembly out. The main brake light is at the top, just twist the socket and pull gently. The bulb just pulls out of the socket.

DO NOT TOUCH THE NEW BULB GLASS! It will cause it to burn out much faster.

Replace the bulb in the housing, and then test it. Once it works, reverse the steps. Also, do not do this if it is very humid or rainy outside. The moisture can get into the assembly, and cause an early failure due to condensation. If you see water inside, take it apart and let it sit in the open to dry out. Then put it back in.

faulty bulb or the connection on the bulb fitting is not good.

check the BAP (barometric air pressure sensor), rainy days mean odd Barometric pressure, so the sensor could be faulty, a simple multimeter can show you what voltage it is putting out, and replacing it on a rainy day might show you that it is faulty as well

Could be due to the high humidity on rainy days, affecting your possibly deteriorated spark plug wires and blocking the spark to the plugs. Have the wires checked to see if they're bad.

Your spark plug wires are breaking down. The humidity is getting into the micro-cracks and shorting them out.
WD-40 sprayed on the wires will remove the moisture.
('Engine electrical' is one of the uses listed on the can.)
Change the wires.

you need to replace the rotors.On new vehicles the manufacturer designed the rotors along with other parts to be replaced at certain mileage or ware.When they ground the rotors they became thinner.So now when the brakes warm up the rotors are easier to warp,which is the problem your having now.

using any type of parking brake on a regular basis prevents the components from locking or seizing up. I set my parking brake at least 2 times a month to keep it exercised. not using it won't burn it, it just won't keep it working