Fossil

The ancient Greek philosopher Xenophanes found fossilized shells on dry land

and concluded that the area had once been a seabed.

The Chinese scientist Shen Kuo found fossilized remains from species

that could not have lived the modern environments in which they were discovered.

oil

the remains of {ancient marine} organisms, such as plants, algae, bacteria (humans, and animals)

You assume too much like it is fact.

"algae and plants lived in shallow seas."

"After dying and sinking to the seafloor,

the organic material mixed with other sediments and was buried."

How were they buried?

"under high pressure and high temperature,

What caused the high pressure?

the remains of these organisms transformed into what we know today as fossil fuels.

Coal, natural gas, and petroleum are all fossil fuels

https://education.nationalgeographic.org/resource/petroleum/

Petroleum can be found in vast underground reservoirs

You assume that it would take billions of years to grow that much oil.

When God cleaned the earth after the Great Flood

He buried the dead plants, animals and humans.

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