That's pretty common when talking about the actions or product of a non-sentient structure. It helps to differentiate the product from the person. If you say "I released a new version", the end result is tied to the individual. If you say "we released a new version", even if it's just one person, it makes it clear that the new version is the output of the company/organization/collective/structure/etc, even if that company/organization/collective/structure/etc is just one person.
It's kind of like a single-owner LLC. The structure limits the liability by detaching responsibility from the owner and attaching it to the corporation, even though the corporation is in reality just the one person. It's a very abstract concept that just implies a product can be separate from the individual who created it.
As for the code, yep I built everything myself (and wrote about it here [0]). But I've also had the help of people translating the app, giving feedback, and making suggestions along the way. Listening to people and filtering ideas through my own vision has really made the product what it is today.
Thanks, though! I'm just excited to keep pushing the AP ecosystem forward and making the platforms on it more usable.
Seriously impressive work by the way, and I'm really happy to see such a well-developed project use Go+ActivityPub.