The very early universe can't be observed with visible light. It was filled with ionized hydrogen and thus opaque over long distances. The oldest light is from the era of "recombination", when things had cooled enough (c. 370k years after the big bang by consensus models) to permit light to travel. This is just the thermal glow of the universe, redshifted (way, way) down into the radio spectrum. And we can see it just fine; it's the cosmic background radiation and has been very well studied.

It's the region between recombination and the currently-visible-to-telescopes galaxies that Webb is particularly well-suited to study.