I can’t say this did or didn’t happen, but I absolutely had ‘philosophical’ thoughts like this as a kid.

When I was ~10 I asked my mom how we know other people aren’t ‘aliens or something’. She just dismissed me as being silly, and I didn’t know it at the time but in retrospect I was absolutely experiencing and asking her about solipsism.

I didn’t know it was ‘philosophy’ but I think it’s integral to how we experience the world and sentience in general.