the boy seems to have been someone who "lived in my mind" if that makes sense.
Imaginary Friends are super common in childhood... including normal & even golden childhoods... a child’s mind is an amazing place; full of endless possibilities and potential, the real & the imaginary often having no boundaries whatsoever.
I always wanted an imaginary friend, but never had one. Not as a child. Not until I was much older & started writing stories... creating whole universes to play in... as I spent countless hours in cars, trains, planes, attempting to fall asleep. By the time I started doing that, the
only place the people and worlds I made up could live were in my heart/mind, and on the page/canvass/clay/whatever medium I was playing with, (and in other people’s hearts/minds). The boundaries between imagination and reality were too strongly set, by the time I started creating things.
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There were ALSO things I swore up & down were real... and was told were absolutely not... that I later found evidence I was right. The adults had just forgotten, was all -OR- the way I described them didn’t make sense to an adult mind. Like I swore for years I had pet fish in Japan, that I fed every day / it was my job, and they loved me so much they tried to come out of the water to hug me... and was told I did not, we didn’t have fish until we came back to the states, and fish DONT do that. Well? I found a pic of me petting the koi I SWORE were real, for years, and was told those were the koi I loved so much at the train station thay every time we rode the train we had to detour to the koi pond, or I’d throw a temper tantrum about not being allowed to see my friends, the fish. My parents? Knew the koi weren’t “ours” so they weren’t “my” pet fish. And that koi surface to be fed/petted/etc. they didn’t see as “coming out of the water for hugs”. Similarly,
everyone fed those fish, it wasn’t my job. And whilst I might have considered the train station part of “home” (I also swore there was a river inside our home, that I was told I was “just imagining”; but seeing the picture of me at 2yo petting the koi in their river in he train station? Yep. THAT’S the river in our house!!!)... because we left “home” every day from that train station, and returned “home” every day TO that train station... it’s hardly insane that a child attaches the train station to meaning “home”).
Just 2 ways of remembering the same event(s).
So whilst it’s totally possible you simply had an imaginary friend, as a child? It’s also possible that the kid WAS someone you knew... but your parents weren’t taking you for a play date. But dropping you off at a sitters. Or the apartment building WASNT an apartment building but a preschool, and you and another child were always there the earliest or latest, so it was your special time, together. Or any of a hundred other disconnects between how a child’s mind sees an event, and how an adult mind sees the event.