Why can gold be found as the element? It is because it is non-reactive?
Well, I think you have answered your own question...........
Gold can (still) be found in the Earth's crust as more or less pure nuggets, and historically this was responsible for several gold rushes in North America and Australia. Because gold is LESS reactive than the transition-metals, it can thus be found as an element.
On the other hand, iron and aluminum, much more reactive metals occur in the Earth's crust as their oxides and sulfides.