My understanding: what’s great about Webb is that it can take pictures in the infrared.

It has to be really cold to do this, hence the big complicated heat shield.

Infrared let’s us see things that are further away, because when something’s really far away it gets red-shifted down out of the visible spectrum into the infrared (due to expansion of the universe).

So it’s not really any better at imaging things that are close / in the visible spectrum like Jupiter.