An infant is born nameless (from their perspective ofc). It is only after some time that they begin to associate the name their parents use to refer to them, as something they are, or possess, something that refers to them. Quickly after this they start to apply names to other things as they have to themselves. Language acquisition has begun. The differentiation or disntiction of "self" from "other". The beginning of object permanence and language permanence.

A name is, probably, the most basic form of acknowledgement of identity. What noun we use to identify ourselves. An infant doesn't know what "human" means, nor "boy" or "girl", nor many other such basic concepts of identity or the human condition. They don't know the word "I" they just have a feeling of it. They don't even realise their hands are theirs until 2 months where "hand regard" is achieved and they find themselves staring at them.

So it seems when they're born they are just in a state of "awareness" without even full knowledge of what is part of their body and what is not.

At most they know a simple Binary - "Good" = milk, warmth, rest and curious observation and "Bad" - hunger, cold, restlessness, pain/illness.

So "who" or "what" does a baby believe it is? Where does it believe it is? What sort of sense of self or identity could this baby have?

It's possible that all babies begin as the "center of the universe" so to speak. A little helpless and innocent solipsist. Not even fully understanding what other people are or if they are even separated from it. Egoless perhaps? Just pure awareness with little to no assumptions or "learned beliefs".

I find this fascinating. And truly innocent. A state where embarrassment, prejudice, bias, shame, guilt, hatred and resentment are no where to be seen. Because these all depend on having a sense of self consciousness, a sense of discrete and defined relationship to the external world.