The situation you illustrate is one of the major reasons why it is important that safety ground connections be kept isolated from neutral connections.
If there were two wires connected to grounds at the left of your picture, one of which was carrying current for the load, and one of which was being touched by the person, then for a harmful condition to occur it would be necessary both that one or more connections failed, and also that one or more erroneous connections was present. Neither any combination of failed connections alone, nor any combination of erroneously-present connections alone, would suffice.
One of the limitations of normal safety ground protocols is that while multiple faults are required to create harmful conditions, it's possible that enough faults may develop that the system is one fault away from electrocuting someone without those faults causing any symptoms. For example, it's important that the safety ground and neutral wire have no connection to each other, except via separate paths to earth, but there's no way short of disconnecting the neutral to ensure that's the case.