Q1: Nick Fuentes isn't a white nationalist/white supremacist. Will someone please change the article's description of him?

A1: Reliable sources describe Fuentes as such, and thus so does Wikipedia. See also WP:SNOWBALL.

Q2: The article's sources have a left-wing bias, or are otherwise unreliable. If Wikipedia is supposed to be neutral, shouldn't the sources used in the article be more balanced?

A2: Neutrality and balance are not the same thing; see WP:FRINGE and WP:FALSEBALANCE. For a general guide on which sources are considered reliable and unreliable according to community consensus, see WP:RS/PS.