Making friends as children is such a straightforward process. You see a cute and friendly looking person of your own size. A tentative sharing of smiles and then a little 'hi' starts the exchanging of names and a bit of shy conversation. Maybe they are thinking 'you are small like me, we giggle at the same things, you look nice...
Before long they were holding hands. I remember making friends like this when little. A simple 'Do you want to be friends - Okay'.