So if without life there they have so much hydrocarbons, why then do we need to believe that our hydrocarbons come from the remains of some dead creatures, whether plankton or dinosaurs?
In the case of oil, the sediments in which deposits are found, the fossils within those deposits, and the chemistry of the oil, all point to biotic rather than abiotic origin.
The paper I've linked in my earlier comment has far more detail and further references: https://news.ycombinator.com/item?id=28105383
Yes, it's possible for hydrocarbons to form by other means. However there's vanishingly little physical evidence to suggest that that is what's actually happened.
Retrosplaining terrestrial hydrocarbon deposits based on remote observation, and one short-lived lander on an outer-solar-system moon (the Huygens probe on Titan, with very limited chemical sensig capabilities) in a hand-wavy attempt to invalidate several centuries of direct terrestrial experience with coal, oil, and gas geology is not exceptionally convincing.
Thomas Gold in the “Deep Hot Biosphere: The Myth of Fossil Fuels” explores the idea in depth.
It’s not quite a crank theory (I think Gold has a legit academic publication history) but it kind of teeters on the edge. It’s one of those ones I’d like to believe, because it turns much of what we think we know on it’s ear. But a sober look at the evidence makes it seem pretty unlikely.