Have you ever gone to rural Ireland. You smell the peat for miles. Its grass that grows every year, covering every inch of land. Then it dies, every year. New grass grows over old to the point where dead grass lies thickly over thousands of layers of grass that has died before. And the Irish literally cut logs of dead grass called peat. They bring it in to their fire places and heat their homes with it. In the North Sea there was land that had been above water a mere 5000 years ago. The land between England and Norway has been named Doggerland. Look it up. It too had thousands of layers of grass. And we harvest that grassland as well when we drill North Sea oil. Peat, Oil, Coal, and Natural Gas are all the same thing, dead grass. And its renewable. Every year we flare off excess Natural Gas from oil wells and land fills. There is a lot of carbon locked with oxygen and hydrogen. A never ending supply. And as we burn it, setting the elements free, they are adsorbed even more readily by the increasing plant life. And more carbon based fuels will be made.
Actually, all coal deposits in America and Europe, (possibly the entire planet), are entirely made of a specific type of tree bark. The deposit layers of which can only be produced in a hydraulic event. But yes, as to your greater point, hydrocarbons are deposits of what was plant matter.