Adding to the answers of others, Webb can't see the whole observable universe. It has an upper limit on wavelengths that it can detect. Because older / further away light sources are more red shifted, at some point the really old / really far away stuff drops off the spectrum range that Webb can see. Here's a nice read [0] which tells me that the oldest things Webb can see are from T = 100-250 M years after the big bang. The light from the [matter around the] black hole in the main article originated at T = 570 M years. So it is plausible to me that an even earlier one will be spotted by Webb eventually.

[0] https://jwst.nasa.gov/content/science/firstLight.html