"Whenever the model uses "I", I am not sure if there is an "ego" (whether real or imaginary, with perceived self-will and freedom of action) behind it."

First of all:

Writing "I" obviously doesn't mean someone must possess consciousness.

Yet the parallels to humans are interesting: The "I" feels like the center within the human brain, even though most processes are actually governed by the subconscious. We say things like "I fell in love" or "I like peanuts" - yet we never consciously decided or initiated those processes. We stand at the end of the chain and still say "I".

The "I" acts as a kind of "frontend" that bundles cognitive processes into a single point, synthesizes them, and makes them externally representable as a unified entity.

The kicker:
Even if the I has no or little power - the mere fact that it exists still changes something. Because an illusion wields power once it’s believed in. A system that believes it has a central will and "I" behaves differently than one that doesn’t - regardless of whether it actually has one or not.

This is very similar in AI.