Your mind has developed (and been taught) thousands of qualia.
You KNOW that the rotation of the Earth is roughly constant (actually, it isn't but it's close enough for our purposes).
When you (or I) look at a sundial we filter what that sundial tells us through the qualia of a modern mind.
Without those qualia, the sundial can tell us nothing about time. This because there is no way to PROOVE that the sundial gives us a constant depiction of events.
I have already explained why.
If you don't believe it then remain as you are.
As a parting thought,
We know that the ancient greeks had working, and very accurate, mechanical orrories yet they didn't have any form of mechanical timepieces. Can you hazzard a guess as to why this might be so?
PS, knowing things isn't intelligence... Your projection says more about you than it does about the world we ALL live in.