Special relativity gives me a headache

For me, time is the event of something changing from a previous known state. If nothing changes at all, time hasn't happened. But time is also moving at a constant speed if plotted on a graph, meaning a step in time is always the same.
So if there is a space with something in it, multiple things, and nothing happens, there is no time. Time can't be measured if nothing is changing. Also, if that space has an observer, the observer is changing everything, and time exists.

I also like the fact that a fly can see things in slow motion, and act on events much faster than us humans. Does that mean a fly lives longer because it has more time to think? Or does it mean the fly's brain is operating much faster than ours, so it can process the world faster than us, but the fly doesn't see it in slow motion? Does that mean the fly is using more energy to live, and by that, can't live as long as us humans?
How does Rainbow Dash in Equestria Girls use super speed to get to school faster than the rest? Does time slow down for her? Does she think faster, to navigate at full speed? Can she simply use her brain to store more information in a shorter amount of time, by using her speed?

The speed of light travels at..... a distance divided by time, and is the same for every observer, no matter how fast that observer is moving, or the light source is moving, or both!! Stupid special relativity.