How do fossil fuels come from the sun?

This question could mean 2 different things so I'll answer both. Fossil fuels are made from plants and animals hundreds of millions of years ago, these plants and animals' atomic structure would be from substances originally created from the sun. When these plants and animals existed hundreds of millions of years ago, these plants would have harnessed energy from the sun via photosynthesis, when the animals ate the plants they would harness the energy the plants had harnessed from the sun, so when the plants and animals died and eventually got buried under mud and rocks to decompose, they decomposed into fossil fuels which still contained the energy they'd harnessed from the sun hundreds of millions of years ago which is being burnt here in the 21st century and used for electricity and vehicles (despite many environmental downsides).