I agree but I don't know if that explains how humans can tell time. If you put a human in a completely isolated room with no lighting changes then I doubt they'd be able to count the number of days.
We can tell time inaccurately by timing somewhat regular internal biological events. That pretty much follows from the definition of time as the interval between regular events (which are assumed for physical reasons to be equally spaced). The only question is which underlying events we use and how.