as much as capitalism has it's flaws, it is easier to explain than most other systems because it is just the natural extension of "I aquired this fur pelt and will defend it" just with a mandatory insurance scheme (government police/laws/military) and more distributed wealth (fractional ownership).
Obviously it is far from the best system, but the core idea is simple: I OWN objects, the object can be any size or value irrespective of it's usefulness to others. It is a system that benefits those with resources at the expense of those that can hardly afford to revolt.
Now explaining the overreach of the government from a capitalist perspperspective is an actually difficult task.