It's not all about the kids. But sometimes it is.
He's sticking to lines or edges of things. The stripe, the fence, the rail. He's orienting himself to those things. That, and he looks like a cute little boy out exploring the world in all of them.
Oliver is dreaming of being a tightrope walker and he's just waiting for the right time to join the circus? :-p
They all have me wishing that I knew what Oliver was thinking about those lines he is observing so closely!