Why You Don't Understand the Theory of Relativity

Einstein's theory of relativity has baffled me since I first read about it. You too? I think I know why.
Relativity has been explained in many ways and has many implications, but the thing I could never get past is that time speeds up or slows down, depending on how fast something is moving, relative to other objects and to the speed of light. Huh?
This is saying that time is a "thing", an object, something tangible, but that is not correct. Rather, time is a measurement. It is like length, or temperature, or speed, all measurements of something else. What does time measure? Existence.
Time is a measurement of the duration of existence, of being. So whether something travels fast or slow, relative to anything or nothing, its existence isn't changing. Time, the measurement of existence, may get altered, but not the existence itself.
Consider the measurement of length. How do we know how long something is? We pull out a ruler, or perhaps a tape measure. Every introductory physics class teaches how steel expands and contracts as temperature changes. So if you want to measure how wide your yard is, using a steel tape measure, you have to do it at "standard conditions" temperature. Otherwise, the tape will be shorter or longer than an agreed upon standard for length measurement, and you come up with an inaccurate measurement.
So it is with existence measurement. Einstein's theory of relativity, though perhaps difficult to apply in practical applications, is telling us not that existence changes with speed and relationships to other objects, but rather that the measurement we make of that existence can get distorted. So sorry, time travel isn't going to happen any time soon.