I would think the Jellyfin logs would say if it deleted something. But I have to say, I cannot fully understand GUID and PUID in all cases. But you can try to subtract 1 digit from PUID (100 to 99) and then try to delete a show or movie within Jellyfin's interface. If it won't do it, then you've got the permissions at least where it can't delete things. It is possible to not view things as well, so it might take some research or trial and error and make sure you write down where it is now. But, it will remove one factor at least.