That part's actually not really anachronistic. Oda Nobunaga was in many ways a revolutionary, radically changing the Japanese economic system, how they waged war, and was one of the most integral players in unifying Japan. The guy had a noted and pronounced fascination with Western culture and reportedly eccentric enough to flip typical respect on its head (supposedly speaking warmly with those socially below him and rudely to those above him). In some ways, the guy is the poster child for the power of bucking tradition and welcoming change and innovation. And yes, this includes being fascinated with the
historical Yasuke (probably the first black man he'd ever seen, as documents of their encounter report that he'd assumed Yasuke had been covered in black ink), who became one of Nobunaga's retainers and fought with him even in the battle of Honno-ji.
Having not seen the series yet, I'm going to take a shot in the dark and guess that the cliche villain you refer to is Akechi Mitsuhide? Because again, that's not an anachronistic portrayal or even necessarily out of character. It's of questionable historicity, don't get me wrong, but the story goes that after Akechi's forces turned on Nobunaga, Yasuke was captured by Akechi's forces, and the latter spared him explicitly on the racist grounds that as Yasuke was not only not Japanese, but just an animal. The argument allegedly went that because of this, it would be wrong to kill him and Yasuke should therefore be sent to a monestary.
Again, not necessarily accurate. There's a lot of debate about Akechi. That said, it's not exactly a baseless interpretation.
