But isn't a lot of H&S aimed at the level of a stupid person.
Basic observations that once read and confirmed you have understood should be then take for read, that someone has to do this.
As an employer, you have to ensure that your employees have information, instruction, training and supervision.
So no, you can't just tell someone how to do a job and leave them to it. Unless you want to be prosecuted for lack of supervision if there is an incident.