So, in the setting I've created, there are many animal and plant materials which are comparable to modern materials and some even greater than what can be made today.
For example, there are molluscs with shells that are comparable to bronze, large lizards whose scales are like iron, predators that have large teeth as strong as high carbon steel and some rare flying monsters even having naturally formed carbon nanostructures within their very bones making them stronger than steel but lighter than plastic.
This extends to plant life as well with some trees with wood that is stronger than the strongest wood in our world and vines that have a tensile strength greater than Dyneema rope.
Why would anyone waste their time with copper, bronze, iron, or low quality steel when a dagger or spear point created from a creature's tooth works better, why have a bronze and even iron sword when a club with animal teeth along its edge works better, and why make suit of metal armor when a fitted suit of sea shells and lizard scales works better, is more comfortable, and weighs less too?
However, this raises the question, in a world with so many natural plant and animal materials comparable and better than what can be made with modern technology why would any civilization develop metal working to make metal comparable to what already exists?