Can humans perceive changes that only last nanoseconds?

Human perception is limited. We can see some wavelengths of the EM spectrum and not others; we can feel some degrees of pressure and not others; we can taste some substances and not others. Our faculties can perceive changes at some speeds but not others.

That doesn't matter because the standard isn't whether our bare perceptual hardware is able to detect this or that. We build telescopes to bring galaxies down to our scale of perception; we build microscopes to bring molecules up to our scale of perception; we build special cameras to slow down speedy events and speed up slow events and shift light, moving the invisible to the human-visible. We build microphones and amplifiers and pitch-shifters to move the inadible to the audible. On and on.

So one way to put it is that yes, in a relatively unimportant sense man the rational animal can't perceive everything -- but in another very important sense man the rational animal can perceive anything.