Hey, congratulations and great job!
I find there's a perpetual equilibrium between feeling confident in your output / yourself, and recognizing that much of what you do will likely be incomplete, messy, sub-optimal. This seems to be a fundamental part of being human as it extends across all types of creation.
Authors have stream-of-consciousness to overcome writers' block. Athletes get the 'yips'. Developers have probably heard "if you're not ashamed of your MVP, you took too long to ship." (does anyone know who originally said this?)
Doubt is a massively powerful and underrated tool that tends to signify the presence of many new variables. It's like a beacon saying "hey this is unprecedented" and the pursuit of any challenge will naturally yield unprecedented outcomes. In your context, you went from "hey let's do a thing" to "the Github CEO wants to call me and talk about this thing and there are multiple people that want to do this thing" and that is pretty damn unprecedented.
I've experienced >3 truly remarkable situations like you, and wandered between inflated ego, utter confusion, guilt, and pure existentialism. Honestly, I'm glad I felt such a spectrum of emotions because in retrospect those lenses provide me a lot of clarity when I invariably encounter another entirely baffling scenario.
I think your self-assessment is as balanced as it can be, and I'm certain that as you continue, you'll adjust the weights (heh) and become more comfortable... or maybe not. Maybe a hallmark of being a creator, founder, leader, is to double down on the discomfort, and rest later. Kind of like a marathon.
I'm following along. Good luck.
P.S. if you see this in time can you ask Nat what he thinks of the federated wiki? https://github.com/WardCunningham/Smallest-Federated-Wiki