I remember pondering a lot of small philosophical points when I was very young, such as:
The color I see in the sky is blue and I call it blue because everyone says that color of the sky is blue. But when someone else looks at the sky, do they see, say, red and call it blue because everyone says that the color of the sky is blue?I remember, years later, hearing about how Descartes arrived at his "I think, therefore I am" conclusion and remembered that I had pondered the same kind of thing as a child.
I also couldn't wait to learn how to read. I knew that all of mankind's accumulated knowledge was written down, most of it in English, and I wanted access. Once I could read, I spent countless hours with encyclopedia volumes spread across the floor around me, as the answer to one question raised another question, which raised another, and so on.
So, that's my INTP childhood (and it's not over).