[dredmorbius]

Actually ... I just looked up the etymology in yesterday's discussion of whether or not petroleum is dinosaurs.

Fossil means "dug up". So both fossil remains (remnents of ancient plants and animals) and fossil fuels are called that because they are dug (or drilled) from the ground. As opposed to harvested fuels (wood, dung, etc.).

https://www.etymonline.com/word/fossil

The popular meaning of "fossil" has somewhat orbited around the usage such that we associate "fossil fuels" with "fossil remains" rather than "dug from the ground".

I don't know if that makes helium a "fossil" resource, though I could see the argument for that. We don't refer to other minerals (e.g., iron, much of which comes from banded iron formations, or limestone, from seashells), as "fossil" resources, despite both being dug from the earth and biological in origin.