I kept all the valuables in a fanny pack and I literally never let it out of my sight. I put it in my sleep sack with me whenever I slept in a dorm and brought it into the shower stalls with me as well. Once I met people where we were sharing rooms and space day after day, we began to trust each other but again, we all kept our fanny pack/waist belts/ with us unless we could lock a door with only our things behind it.
The odds of theft are very low I'm sure, but you never know who has access to spaces and really, it would be a catastrophic thing to have your passport and money taken.
Side note, many showers had no where to put things down inside - clothes, towel etc. On my second camino, I brought an S shaped hook in my toiletries bag and it kept my stuff way dryer!