Because it is made of hydrocarbons.
Going by the total number of different molecules it can be part of, Carbon is the most reactive element. More than the rest of the periodic table combined.
This means that you can make a lot of things out of carbon, such as the examples you listed. Oil is therefore used because it is a ready source of large quantities of carbon.
While there are other sources, the simple fact is the industry is already set up for fossil fuel exploitation.
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