The Terminator could easily crush John Connor's head

The hand-to-hand fighting is indeed ridiculous and comparable to the absurd dog-fighting seen in Star Wars, inspired by arial combat as occured in the 1940s in planes constrained by areodynamics. If the "singularity" happened and machines iteratively designed machines to kill, they'd be unfathomably quick about it. You might not get time enough to realise what was happening unless you happened to be last in the quickly computed list of many targets. No doubt humans could design better killing-machines than these ones supposedly made by this singularity. They'd also have more sensors than a couple of cameras built into a "head" and couldn't be blindsided. They'd sense in 360° on every axis and in the Skynet facility they'd be networked and sense from sensors mounted on walls or wherever. You couldn't hide behind a cabinet; you'd been "seen" from multiple angles at all times by all machines.