For those who are curious, preset and characters files are saved in a directory adjacent to where games are saved.

On a Windows machine this will be in under your user directory:
C:\Users\{username}\AppData\LocalLow\Ludeon Studios\RimWorld by Ludeon Studios\PrepareCarefully

The .pcc files are character files. The .pcp files are the presets. They are all XML files and can be opened and edited in a text editor, if needed.

I don't run the game on Mac or Linux myself, so I'm not sure where those files are in those operating systems. Hopefully, someone can post the information below.