Oh, yes, the range of the human classes and cultures in B5 was greater than SF generally showed then. I think by now the SW franchise has done a lot with in-universe marginalized groups, but not much before 1999, and the framework is fantasy space-opera, not real-physics space-opera.

I have some complicated opinions about Delenn, but it boils down to her being the centerpiece of the main B5 plotline. Sheridan and Sinclair command the station to be the "Captain Kirk" that keeps the fan base (probably including JMS himself) happy, but she's running, or at least keeping up with, the multi-race fate of the galaxy's sapients. It's remarkable sleight-of-hand.