To me if anything has any properties and have anykind of motion or any kind of physical interaction with anything it makes time because it creates a before and an after. And this before and after is valid anywhere in the universe, wether there is or not motion there, because something HAPPENENED and because supposedly, with everything interacting EVERYTHING might one day be transferred it's motion or whatever physical event.
But if nothing ever happened anywhere there would not be any way to distinct any before or after or future.
Now, if you want to mesure something you are in need to use a motion/something happening whatever it is even if the whole universe have only one particle doing anything, if its the case that only motion makes up the time for everything else, but because so much shit actually happens at the same time everywhere, time is the time that every of those objects doing shit create by creating a before and after.
That's kinda why I say it's subjective, because every object creates a before and after by their motion or interaction etc etc.. there is no proper way to describe time if it aint relative to something in particular, it's kind like a gigantic superposition of every particles interaction and because there is not one elementary particles with special rules thatapplies to everything, time is made up of all the befores and afters created everywhere for everything to one day be a part of.