By no means an expert but looks like it’s all from the ground up. My house the said to not do wood on the slab because the ground was too wet and it would destroy the floor and is we but a barrier under it it would just go to the walls and “wick” up. The other possibility is your roof leaks into your walls. And another is you have a cinder block foundation and they are leaking and filling with water then it wicks up the walls.