There are words that distinguish between types/degrees of intelligence. Basal/proto intelligence applies to cells and bacteria. Somatic intelligence is a level higher at tissue. Superintelligence you've no doubt heard of.
It's true that "intelligence" is general/umbrella and doesn't have much meaning, but more specific terms do exist.
A cell is a system, as is a virus, a tucan, a human and an LLM. They exhibit different levels and brands of intelligence, hence continuum.
That's the popular view among scientists/philosophers/my podcasters, at least, and it makes sense to me!
I was thinking more that something like this:
> any system capable of doing an if-else is intelligent to a certain degree
could probably be getting quite broad in terms of things covered (chemistry, physics), hence making it much more intrinsic.
As a crisp example: a newly dead person is almost exactly the same stuff as an alive person, but has no intelligence at all. Not a little less, as the difference in stuff would suggest.