I know I assumed Fossil Fuel = meant the fuel came from fossils, and the first thing that comes to mind when I hear "fossils" is dinosaurs.
I just never thought to look further than that.
Fossil fuels are fuels that are dug from the ground, rather than harvested from plants (as with wood or olive oil ... itself the original "oil") or animals (as with animal fats and oils).
https://www.etymonline.com/word/fossil
Oil indeed comes from olive: https://www.etymonline.com/word/oil
Coal is a piece of wood: https://www.etymonline.com/word/coal
Carbon is from coal: https://www.etymonline.com/word/carbon
Effectively, the word fossil has done something of an orbit such that an attribute used to describe an object ("dug up" -> petrified remains of plants and animals) came to be ascribed to the word itself, such that "fossil fuels" comes to be popularly interpreted as "remains of ancient plants ... or animals" rather than "dug up fuels".
Similarly, I think a lot of people think dinosaur fossils are all dinosaurs who died when they went extinct, because if fossils are dead dinosaurs, and dinosaurs are famous for dying out, those must be connected, right?
Whereas of course dinosaurs had actually been dying (and starting on their way to being fossils) for millions of years before the extinction event which… actually stopped them from dying any more.