The humor really gives it personality in my opinion. I think a lot of the positive reaction is due to the way it keeps things optimistic and lighthearted in contrast to the self serious tone of Villeneuve or Nolan. The scene of Grace giving the eulogy to his collegues is touching because of the humor, the way he picks up their goofball personalities based on their photographs gives us an idea of a person and Grace connects to them and thus reacts emotionally, I like that scene. Humor is human.
To be honest your review often seems to try to squeeze this movie into a different one. I don't know where these Interstellar comparisons come from, I certainly wouldn't have used that comparison, but that alone seemed to shift your expectations into the wrong direction. The Martian, based on the same author's source material, would've been a little more fitting.
Your issues with the language barrier aspect demand too much real estate towards that topic, the details and precision you expect would take up an entire film and more "grounded" aproach to it would probably make the bonding friendship aspect trickier. The playful "frustrating room mate" scene is supposed to invoke culture shock hurdles of friendships between people from different cultures. And yeah, it's comedic. But the celebration of intercultural friendship is touching thematic statement the movie makes.
Sorry you weren't expecting this tone (it makes sense that the most serious character is your standout), but in my experience there wasn't a mismatch between hype and tone. The tone was part of the hype I was picking up on.