Yes - that is how it is thought about, but of course, fossilised carbon in the form of oil and coal and even much lower carbon releasing methane gas, is permanently locked up right until we dig it up and set fire to it. Once out in the open, that carbon - now carbon dioxide, may be absorbed by trees or other biology, but even when it is, and we create a forest, that forest eventually decays or is burned and the co2 is back in the air, so as you suggest in your first sentence, the idea that we can mitigate the release is in fact delusional - at least in the ways we try to mitigate carbon release at the moment. If it were permanently put under ground in some manner, that would be different.
So - once that carbon is released from oil or coal or gas burning, it is pretty much out and free for the foreseeable future. There are natural permanent de-carbonising processes, they are pretty much the same ones that the planet used to make our oil, coal and gas reserves, but they are VERY VERY slow, operating over millions of years.
Your remarks about the bio mass burning are on point. There never was a worse example of greenwash than suggesting that chopping up American ancient forests, chipping and drying the wood and shipping it over the Atlantic to be burned at Drax, is in any way a green solution. It is a monstrous lie and a terrible environmental crime. The wood chip companies are supposed to use waste wood and trash from forestry operations - the branches and side shoots, but they have been filmed chipping whole trees in huge numbers.
