This may sound crazy but who was the first person or being ever born from the Backyard? Or rather who is the first Backyard Resident ever born into existence?
It’s difficult to trace the Backyard’s history as it may in fact eclipse Human and Non-Human History alike.
Assuming the Backyard has existed for several Trillions of Years or more (longer than this Universe’s History), it would be next to impossible to trace any connection or distinction between Life born of this plane of existence or the Backyard.
Axl Low is the only known being in existence to have travelled several million years in Earth’s distant past (as suggested in GGXPlus artwork), but assuming his powers held sway over the Backyard in that era, it wouldn’t be nearly close enough to determine Life’s origin in the Backyard.
Assuming the Backyard had connections with Humans directly, “life” could have existed as early if not earlier than “Human thoughts” or “Dreams”, as Bedman postulated. But that assumes Non-Human Life has no “thoughts” or “dreams” of their own.
But then you’d have to ask the question “Which came first?” Thoughts or People?
For now that’s all I can say. Izuna is the oldest ‘known’ Resident to our knowledge.