I don't like them either. :/
Sometimes they can be funny "just for the lolz".
But when they're "serious" human Kirby fan art, they make me cringe really bad.
Ironically, I don't have any issues with humanized Adeleine.
If I'm not mistaken, it was said somewhere that she was a real human, that came from Earth.
She traveled to PopStar to study it's scenery for artistic purposes.
I don't really remember where this is from. Some say it's from the Kirby 20th anniversary encyclopedia (but I guess it isn't) and some others say it was from the Kirby 64's japanese game guide.
I take it as canon, personally, but I won't state it as official until we find the source of this.
This also may imply that the Kirby series takes place in the future, where space travel is advanced enough for humans to live in another planets.
The fact that Kirby met Samus in Kirby's Dream Land 3 also makes this theory very possible, since in the Metroid series, the Earth was destroyed or something.
But apart from that, I never saw Adeleine as a "Poppy Bro" kind of being.
She always looked anime-ish to me too.
And I guess she was intended to look like a "manga" human as well.
You see, her in-game graphics are limited by the Nintendo 64's graphic engine.
The artstyle they went with Kirby 64 didn't helped as well, since everyone looks kinda different in that game. (just look at Dedede!)
But I guess that, if they remade Kirby 64 with the series current artstyle, Adeleine would look more like a anime human child than anything.
The only thing she lacks in the game is a nose, and a more proportional body.
But again, this could be because of this game's simpler artstyle.
Because, in the game's credits, she looks very human. (With a nose and a more realistic proportion.)
Also, in Kirby's Dream Land 3, Ado (who is, supposedly, Adeleine) looks like a "anime human" in the credits too.
So, anime Adeleine fanart doesn't bother me too much.
I just don't like when they sexualize her. She's supposed to be a kid, after all.
But... what can we do... R34 is everywhere and there's no way to escape it.