So...nothing got older before humans existed?
You're confusing things wearing out with the measurement we use to gauge the rate of that change. Your question is a little like suggesting that I am claiming that before they invented feet or meters, that the moon touched the earth. Our bodies wearing out is no more a result of time than the distance to the moon is a result of the metric system.
We decided to call duration 'time' - we did not create it.
That is correct. Therefore change existed long before humans. But the entire construct of the increments we use (and call time) did not exist. We are so proud of our units of time that we have become completely intrenched in them to the point that we even consider them to be literal as if they are a place to be traveled to. We have forgotten that they are merely man made increments to measure the rate at which things change. We can not travel to the "place" of 1955 (as in the moving Back to the Future) because 1955 is not a place it is only a chalk mark on the wall to remember the way things were.