What trap do you feel like all these canceled adventures have done that My Hero and BC avoided? I agree with what you said but I’m honestly curious. I didn’t think MHA got good until Deku arrived at UA. BC I’m unsure of when the jump of enjoyment occurred for me cause I’m not sure it occurred yet.
Most important aspect I feel is character development. Just look at every series successful in Jump atm and compare how you felt for the MC after ch 1 compared to all the fodder. Generally fodder have vague, underdeveloped characters. Look at Jujutsu Kaisen for example, 2 chapters in and it doesn't feel like the author has given the MC any life, or reason for us to care for him. Compare to MHA, and the "You can be a hero" moment practically gives you shivers because we've been shown Deku's struggle and resonate with him.
Same with TPN, they introduce us to these kids and how they're all living such a great life with their siblings. It brings you into their life, and then we're hit with the surprise and it's devastating.
In BC you finish the chapter outright annoyed at Asta, but at least you
know he's annoying, and you're not sitting there trying to work out what sort of character he is.
Red Sprite and Demon's Plan are examples of this done badly. After 15 or so chapters, I didn't care enough for the MCs to even know their names, let alone other characters, yet TPN, MHA & BC all accomplished that in a single chapter.
Golem Hearts on the other hand never really developed Noah enough for us to be able to care for him, and there wasn't even a particular moment that tried to make us feel for him either.
Bozebeats at least tried with the Wolf mother's death, but wasted it because the MC was underdeveloped and basically a psycho who'd done nothing at that point.
Pacing is another thing. I feel having a conclusive first chapter that builds up to a climax (unlike Jujutsu Kaisen, Golem Hearts) is extremely important for creating impact, otherwise you're just there like "wait, what? it's over?", which ruins the setup. They introduce characters and the world, present a problem (and sometimes solve it) and then leave the rest for later. I think Bozebeats actually handled this bit well.
World building - does the author properly articulate their thoughts? Golem Hearts left us with no explanation of the battle system or really anything about the series, so how are we supposed to understand and care? Noah's Notes completely explained it's concept. Jujutsu waited until chapter two, and even then it's vague. People can complain about Black Clover as much as they want, but since page 1 the series has always known exactly what it wanted to be and it went with it. The start of the series was quite solid, explaining the magic properly, societal issues (royals vs bums), the whole kingdom thing, supporting character's relationship to MC as well as both of their goals, reasons behind them, and finally, a conflict. Although the premise itself wasn't great, its solid and not vague in the slightest. Which is ironic, because premise is normally what we look for to grab our interest in a series, but if it's not executed properly, it may as well be a shit one, so I don't think it's as important as common sense leads us think.
All of this and I haven't even got into the more obvious aspects like art, premise, character personality. So while I think Noah's Notes was well written, I don't actually think the characters themselves were particularly good (but they were developed well). Though I feel like that's somewhat less important in the scheme of things (See Banba the Man & countless other great MCs from fodder who were dope, but neglected by the author). Its easier to recognise all this on some series more than others. Like I honestly dont know where I’d put Act-Age in any of this because it’s so unusual, and I feel like I can only generate a superificial opinion of “MC annoyed me so I dont like it”.
Essentially it comes down to whether the author has their shit together or not. They present a world and characters that feel alive and then hook you in with something.
Sorry for the wall, I tried to be analytical and shiz for once. I'm probably just spouting nonsense and this stuff is decided by 10 year old kids.
Well, can't wait to see Ziga. I hope it won't flop like Bozebeats
Seeing that is kinda a downer considering what happened with Bozebeats...