Goblins are people too! Don't be fooled by the fake-news-race-hate! Save a goblin now!

You are right that it is not that normal a depiction for Goblins. Often they are shown as dirty and primitive, with limited speech, which I think used to be their canon description. I have no idea what 5e goblins are supposed to be like but the game sort-of matches this link

https://www.dndbeyond.com/monsters/goblin

Beyond the physical depiction, I suppose they want to use speech that makes sense to the majority of the modern audience, just as humans no longer speak as Shakespear would have. It would be interesting to have each race with a distinguishable linguisitic culture, but it may not be canon, and would require a lot of thought.

I don't know about the other anomalies. They may have plot/story links that you can uncover, or may be accidental and will be fixed. It is still pre-alpha, after all.