It's contradictory feeling but it's often easier to know more about small things far away than small things nearby. The reason? Light. Webb was able to detect

It's contradictory feeling but it's often easier to know more about small things far away than small things nearby. The reason? Light. Webb was able to detect the absorption characteristics of PAH (the organic molecules in question) from a distance because there was light from behind illuminating it (and it was absorbing only parts of that light). We know roughly what the light being emitted "looks like" so we are able to extrapolate based on what light isn't present what is in that region. And it wasn't as if individual particles were being seen but rather there is a sufficient density of these molecules spread out in the regions where they were detected that when the light passed through them, it was noticeable from a distance. Kinda like how you can't see the air but you can see the sky. I'm probably not explaining it super well but it's the phenomenon where you can see the gaps in between up close but from far away it looks like one big blob. But point being Webb was able to make that discovery because those molecules basically had a giant lamp shining on them from behind and we the observer are at such a distance that we can see all the little bits of information that would otherwise be indistinguishable from noise all together at once. Now comparatively, the stuff out in the far reaches of our solar system have a lamp shining on them (our sun) but we are on the wrong side to be able to see the shadows that are cast. So unfortunately that means if we want to learn about this blindspot of ours we have to physically go out there to see it.