Me too as my anecdotal evidence is completely opposite of you, neither myself or anyone I know would get a reference to ATLA, I vaguely know about it because of the anime being broadcasted in some channel.
These are all late 20s, early 30s people, Brazilians, Scandinavians, Germans, Dutch and so on, 1984 would immediately be known by most, quite a few have read it, none (even if they know about ATLA, what many don't) would get the reference.
Interesting I can cite a conversation I had not long ago with them to act as anecdotal data, I'm really interested to see what is the split here.
"Anime" as a word isn't even a genre. Its... incredibly ill-defined.
Actual genres would be "Shonen" (Dragonball Z, Full Metal Alchemist, My Hero Academia), "RomCom" (Ah My Goddess, SNAFU), "Magical Girl" (Sailor Moon, Pretty Cure), Mecha (Gundam), "Sci Fi" (Cowboy Bebop, Ghost in a Shell), "Mindfuck" (Evangeleon, Paprika, Paranoia Agent), or "Isekai" (Overlord, Sword Art, Slime)
And a few shows are blend between genres. Both Inuyasha and Kenshin are Shonen + RomCom blends for example. There are a few shows I can't pin down exactly (Little Witch Academia doesn't seem to follow any genre rules... too many action scenes / stress to be Iyashi. Not enough transformation scenes to be magical girls. Not cute enough to be a moe. Too much supernatural to be slice of life)
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Each genre of anime has its own art style, expectations, and writing style. Avatar would probably be a Shonen if I were to pin it to a specific genre (Child protagonist, action scenes aimed primarily at young male audiences... a "Shonen" or young male demographic). Avatar's artstyle is reminiscent of Shonen as well.
Both Paprika and "Night is short..." are anime and considered anime by the whole community. But stylistically, they are no where close to Avatar, DBZ, Full Metal Alchemist.
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The most consistent definition of anime is Japanese origin, or at least "Eastern" cartoons. "Anime-style" describes Avatar, Teen Titans, and RWBY. But its not really acceptable in the community to call those shows "anime". But I guess if we want to get technical about genres and definitions, "Anime" is a word that's too ill-defined to really be useful in these kinds of discussions.
I don't think you speak for the entire community. In the anime communities I frequent, it is perfectly acceptable to call ATLA an anime and nobody will bat an eye.
These are all late 20s, early 30s people, Brazilians, Scandinavians, Germans, Dutch and so on, 1984 would immediately be known by most, quite a few have read it, none (even if they know about ATLA, what many don't) would get the reference.
Interesting I can cite a conversation I had not long ago with them to act as anecdotal data, I'm really interested to see what is the split here.