(I'm a mod here)
It's true that this place can be cryptic, and that has downsides—specifically, it can be confusing to newcomers, even to some newcomers who would make ideal HN users. That sucks.
But there's a key that unlocks most of the puzzles. That is to understand that we're optimizing for exactly one thing: curiosity. (Specifically, intellectual curiosity, since there are other kinds of curiosity too.) Here are links to past explanations about that: https://hn.algolia.com/?dateRange=all&page=0&prefix=true&sor...
We try to elevate things that gratify curiosity: creative work, surprising discoveries, deep dives, technical achievements, unusual personal experience, whimsical unpredictability, good conversation, etc. And we try to demote things that run against curiosity, especially repetition, indignation, sensationalism, and promotion.
It gets complicated because you'll also see plenty of repetition, indignation, sensationalism, and promotion on HN—alas! This is the internet after all. But the site survives because the balance of these things stays within tolerable ranges, thanks to two factors: an active community which cares greatly about preserving this place for intended purpose (https://news.ycombinator.com/newsguidelines.html); and an owner (Y Combinator) that pays us to work on the site full time and mainly just wants us to keep it good, to the extent possible.
If you really want to figure this place out, the way to do it is as a reader. Hang out on the site, look at the mix of articles that make the frontpage, spend time in the discussion threads (hopefully the interesting sectors and not the flamey ones!), and over time your eyes will adjust.
What doesn't work—and this is good because we want it not to work—is approaching HN as a platform for promoting content. If you (<-- I don't mean you personally, but anyone) mainly care about "how can I use this thing to get attention for my startup/blog/project/newsletter", then you're operating in 'push' mode rather than 'pull' mode (or 'idle' mode, which is even better). In that case you won't be curious because you're too focused on what you're wanting for extraneous reasons—and if you aren't in a state of curiosity, this place won't make sense. At least we hope it won't!