If this is the top of your list of what's wrong with the plot of Interstellar, it feels like you're really nitpicking.
1. It was clearly established he was an ex-pilot for NASA. To describe Coop as just a farmer is horribly misleading.
2. We don't actually know what happens in a black hole. There was certainly some questionable science in the movie, but given that they gave an explanation for what happened in the black hole, and we don't know what really happens to contradict the movie's explanation, this seems like a valid use of artistic license.
1. It was clearly established he was an ex-pilot for NASA. To describe Coop as just a farmer is horribly misleading.
2. We don't actually know what happens in a black hole. There was certainly some questionable science in the movie, but given that they gave an explanation for what happened in the black hole, and we don't know what really happens to contradict the movie's explanation, this seems like a valid use of artistic license.
3. I'm not even sure what this means.