Quick warning gang, Inscryption is one of these games that is best experienced completely blind. If you clicked on that post thinking "wowie! I sure do love hearing Verse's thoughts even on games I know nothing about!" I strongly advise you close that tab and buy Inscryption right now. It's a good game trust me on this.
Anyways. If I had to say what Inscryption is about, on a surface level at least, I'd say that it's about video game characters coming to life. This is absolutely not the first game to explore the relationship between characters and medium (Undertale/Deltarune and Everhood come to mind) but there are two major differences in how Inscryption handles it.
First: none of the characters in Inscryption are human. Mindset-wise, I mean. Usually, these sort of games play up the "if YOU were in a video game you'd react badly over this too" because, well, that's a very human reaction, and people want you to empathize with the characters. Not here though. Leshy, Grimore, P09 and Magnificus absolutely do not have reactions like you or I would have. They're not human! They don't have human wants or perception of their worlds. They don't give a shit if they only exist in a video game. No identity crisis here. What they care about are their internal politics, how their world is rules, and thus ultimately what kind of game Inscryption should be. (Hell, Leshy seems perfectly fine just gaming against players all day, considering how he acts with Luke & Kaycee.)
Second: the relationship between player and characters is that of an outsider in a new world. You're not possessing an existing character who would have opinions on that (Deltarune, Undertale, Everhood) you're not here for some big reason (everhood again.) You're legitimately just some guy playing a game. For Leshy, you're a new gaming partner. For the other three scrybes, you're finally a change in the current power balance, which they can use for their own goals.