In your example the persons are the resources which actually do the work. Each person can work in the displayed position, but the position itself is not a resource in this case. The same is true for the relationships of the persons to the organizational unit. The persons are part of it and they are the ones which do the work, in case the organizational unit is assigned to a function.
Regarding the evaluation of organizational structures by the simulation you can also have a look at the ARIS help topic "How organizational charts are included in the simulation".