idolo

The first sense is religious, and it is a judgement. An idolo is an image worshipped as a god, and the word has never been neutral: it is what the scriptures of one religion call the gods of another. That is worth saying plainly rather than dressing up, because a learner meeting idolo in a templo is meeting a term of criticism, not a term of description. The neutral word for a carved figure is statuo at 1,690. Idolkulto and idolservo are idolatry; idolano is an idol-worshipper. Esperanto's own writing on religion is unusually careful about this vocabulary, and this chapter's article on Esperanto and the religions is where the register is discussed at length.

The pop sense: yes, it is dictionaried. The Reta Vortaro gives idolo a second, figurative sense - a person or thing admired to excess - and that is the sense doing the work when a singer is somebody's idolo. So the third example above is good Esperanto, not a calque. It is worth knowing that the figurative reading carries a faint edge of disapproval in Esperanto that English has mostly lost: idolo implies the admiration has gone past what the object deserves. If you want the neutral version, heroo or modelo will do it.

And it is an image word underneath. Greek eidolon is a thing seen, a shape, a phantom - the shade of a dead person in Homer. The step from a phantom to a carved god to a teenager's poster is one long argument about what it means to worship an appearance, which is precisely the argument the word was invented to have.