So the thing about comedy is that the more you analyze it, the less funny it becomes, at least for me. You either laugh or you don't. It's hard to analyze how funny something is when you're reviewing, cause you tend to overthink things when you're in that mindset. That's why I suggested live-testing things. I did some stand-up in law school to help with my public speaking, and it was a good experience for me. Plus you get a better sample size, and it's not just one guy's opinion. But I totally understand you not wanting to do that. But yeah, I think that's the best way, personally. It's especially helpful for working on delivery and phrasing.
Hope you didn't take my comments too hard. I always try to tell people things I liked and things I don't like about their work. Doesn't mean it's bad, just my opinion and suggestions. I always try to explain my reasoning for saying what I do. If my reasoning makes sense, then it's probably good advice. If it doesn't make sense to you, then I wouldn't feel bad at all if you just ignored it.
By the way, I thought "Call me Ishmael," was a good line. When I mentioned jokes flying over people's heads, my exact words were "[that's a] perfect joke for this audience, but sadly I fear this endeavor will fly over the heads of most outside of TNBW." That was more of an observation of the general public, not about your story. I didn't mean to imply you needed to explain things more. In fact, I think you should explain jokes less, definitely not more. The less words, the more punchy it is, you know what I mean?