Great distinction. But, in terms of your example, I am left wondering how much a picture of two people helping each other climb a mountain really adds. It illustrates cooperation - but audience members would have understood that already.
This 'photo to metaphor, to support content' approach just doesn't feel like it does much 'heavy lifting' for the presenter. It works for bland material, but not so much for something like financial services, or pharma, or anything complex really.
They are royalty-free, iconic-like graphics for download that can help illustrate your message. The library is still growing, but you can mix and match graphics to design your slides.