Deku didn't stay quirkless for long, but what if he never got All For One?
Horikoshi explored this possibility in his earlier one-shot and created a character who became a vigilante relying on gadgets.
Another option is Deku becoming a student of the Support Division and working on gadgets or training the heroes due to his observational skills.
Or he would have joined law enforcement because of his inherent heroism.
The "what if?" scenario always feels interesting, especially if it has the basis of the earliest drafts of the released work. The same thing can be said about My Hero Academia (Boku No Hero Academia): when Kohei Horikoshi was outlining his story he thought at first that Deku would remain quirkless but wouldn't abandon his idea of becoming a hero — he'd just rely on gadgets.
This, however, is not the only scenario, so let's think about different ways Deku could've been explored should he stay quirkless. He's naturally heroic and cannot stand injustice in any way, so even without All For One he'll try to find a way to help people, even if it would be against the law.
The multiverse of Dekus
The vigilante route was developed by Horikoshi in the 2008 one-shot My Hero, where the protagonist, Jack Midoriya, is an office worker by day who works selling hero support items, but at night he tries to become the hero he always wanted to be by using the tools at his disposal.
In the earliest drafts of MHA, Deku was a high school quirkless boy who got his powers from using various gadgets. He was almost like Batman, leading a double life. He wasn't called Deku, though — his name was Mikumo Akatani and he was able to fight on par with heroes with quirks by using his analytical abilities and various gadgets. This version of Deku was more edgy and filled the vigilante trope better than anything.
Another possibility for Deku is to join the Support division and become a person who develops the gadgets based on the specifics of certain quirks and their downsides or trains heroes in order to maximize their output. His knack for analyzing the fighting styles of other heroes would come in handy in this situation, allowing him to offer the heroes an outside perspective. There's still a lot of potential for the drama as he still dreams of being a hero but cannot contribute to society in the way he wants despite being so close to those who do.
And a third option for him that seems plausible is to join law enforcement. Sure, in a world filled with people with quirks police seem almost useless, but for the quirkless version of Deku, it seems one of the most plausible options to become a direct savior. Not all crimes are committed by the usage of quirks, and in some cases, he still can be useful. He wouldn't be able to just revert to a simple office job due to his naturally heroic personality.
Which one seems the most interesting?
All these scenarios would lead to a different character development. The quirkless version of Deku will probably be less outgoing, harsher, and a loner. Would you like to see this type of Deku, or do you prefer the one that Horikoshi has chosen?
So, Canon Deku or Quirkless Deku?
Alternate Universe — Canon Divergence.
Summary:
Deku didn't stay quirkless for long, but what if he never got All For One?
Horikoshi explored this possibility in his earlier one-shot and created a character who became a vigilante relying on gadgets.
Another option is Deku becoming a student of the Support Division and working on gadgets or training the heroes due to his observational skills.
Or he would have joined law enforcement because of his inherent heroism.
The "what if?" scenario always feels interesting, especially if it has the basis of the earliest drafts of the released work. The same thing can be said about My Hero Academia (Boku No Hero Academia): when Kohei Horikoshi was outlining his story he thought at first that Deku would remain quirkless but wouldn't abandon his idea of becoming a hero — he'd just rely on gadgets.
This, however, is not the only scenario, so let's think about different ways Deku could've been explored should he stay quirkless. He's naturally heroic and cannot stand injustice in any way, so even without All For One he'll try to find a way to help people, even if it would be against the law.
The multiverse of Dekus
The vigilante route was developed by Horikoshi in the 2008 one-shot My Hero, where the protagonist, Jack Midoriya, is an office worker by day who works selling hero support items, but at night he tries to become the hero he always wanted to be by using the tools at his disposal.
In the earliest drafts of MHA, Deku was a high school quirkless boy who got his powers from using various gadgets. He was almost like Batman, leading a double life. He wasn't called Deku, though — his name was Mikumo Akatani and he was able to fight on par with heroes with quirks by using his analytical abilities and various gadgets. This version of Deku was more edgy and filled the vigilante trope better than anything.
Another possibility for Deku is to join the Support division and become a person who develops the gadgets based on the specifics of certain quirks and their downsides or trains heroes in order to maximize their output. His knack for analyzing the fighting styles of other heroes would come in handy in this situation, allowing him to offer the heroes an outside perspective. There's still a lot of potential for the drama as he still dreams of being a hero but cannot contribute to society in the way he wants despite being so close to those who do.
And a third option for him that seems plausible is to join law enforcement. Sure, in a world filled with people with quirks police seem almost useless, but for the quirkless version of Deku, it seems one of the most plausible options to become a direct savior. Not all crimes are committed by the usage of quirks, and in some cases, he still can be useful. He wouldn't be able to just revert to a simple office job due to his naturally heroic personality.
Which one seems the most interesting?
All these scenarios would lead to a different character development. The quirkless version of Deku will probably be less outgoing, harsher, and a loner. Would you like to see this type of Deku, or do you prefer the one that Horikoshi has chosen?