Resources are both human and non-human. The human resource is primarily labor. Non human resources are land and capital.
The supply of all resources is just what we have today and increasing it in the future requires sacrifice.
All resources are limited. One need only visualize a crowded downtown street to realize that the most desirable location are scarce. Capital is also in short supply because its production requires time and foregoing consumption goods. Even labor is not excessive because none of us have spare time to waste in our adult working years.