Not hard to figure out what a stable orbiting body was doing 41 revolutions ago, even if you weren’t around.
Otherwise you have to concede that the universe may have come into existence twenty minutes ago - all you have are some vague memories that may have been created then too.
The Pluto system is anything but stable. It’s an extremely chaotic system.
Pluto could be a former moon of Neptune... or it could be a Kuiper Belt object perturbed from a more distant orbit... or it could be a captured interstellar object. There are many many possibilities other than “as it is now, so it always was”. Planetary formation theories are extremely raw, wild guesses, and new data constantly forces changes to them rather than confirming existing hypotheses.
As a very direct example of why it is not stable, using only the information from this article... Pluto is losing atmosphere. That atmosphere has mass. What happens to an orbiting body that is constantly losing mass... is that orbit going to be remain stable?