I remember a few things from when I was a baby/toddler. The strongest memory is the confusion around why I was "me", since I was experiencing reality from my totally-subjective experience and I didn't understand why I wasn't someone else. Did all the other people around me have this similar sense of being themselves? Why am "I" trapped in myself? These concepts were scary to me and really distressing, and I didn't know how to talk yet, nor could I really understand anything yet, so it was extra scary and just super difficult to make sense of. To give a sense of what my age would have been, I remember experiencing this while being in a crib.

Later in life these same sensations evolved into pretty much nightly existential dread, and it's taken me decades of "I'm not thinking about this" to not have panic attacks about inexistence and the extreme temporariness of my self.

Due to my early life experiences I never really dismiss a baby crying as something inconsequential like "awww he's [hungry/tired/whatever]!" because for me I was often experiencing some really primal variation of existential terror before I could even speak.