Chemicals are the most vital element that we have in our modern world. Without them the modernisation of our society, and industrialisation could not have occurred. Even before this the use of certain naturally occurring chemicals were still used by our ancestors. Most of these were derived from plants and animals so they offered very little toxic threat. However, the use of created chemicals from artificial means or by the adaptation of natural resources, was very much a different story. In any case they would have wanted to have some Spill Kits, like those from hydepark-environmental.com/spill-response/spill-kits to clean up any mess, much as we do today.
The first use of chemicals that we have discovered appears to be from berries and flowers such as daisies and blackberries. When added to boiling water they will change and stain the water. Plain wool and cloth is then added to give the garments colour. We also know that they were able to make rudimentary paint ( a definite chemical base) to decorate themselves and cave walls. We also know that they were soon using arsenic and copper to make bronze and were soon experimenting with additions to iron. These were mainly trial and error.
From the fourteenth century onwards the Renaissance brings the transition from mediaeval feudalism to the start of modernity. The increase in food and manufacturing is in part down to an increased understanding of chemicals and what they can do to help industry and production.