There are the seams around the door frame and tile in the bathroom. I'm not sure if the black dirt in is mold or mildew, but at least it's not very clean. The relative humidity is 50%, but the bathroom has not been used for a long time.
I would like to seal these seams to keep water out, and wonder what I should do. Shall I clean the black dirt in seams, which it quite difficult, and how? After cleaning, Is caulking with silicone the right thing to do? Shall I fill some large seams with something else before caulking? Thank you.
Edit: I removed the tile and some door casing paint in the first photo, and some paint and cover (paper maybe, it is the right material to be used here?) over the drywall, and photos are added. I have tested with tissue paper and confirmed the door casing is dry. It's the bathroom in the basement, close to the exterior foundation wall. The shower door sweep is missing, I guess water came out from the gap when it was in use.