Kits are tied to Projects. So, the preset Kits that come preloaded with the Rytm are attached to the Presets Project – the one at the top of the list when loading a Project. To copy one of these Kits over to one of your own Projects, see void’s comment here:
Also (top tip!): Always, always save a new Kit when starting a new Project/Pattern before changing things, otherwise it changes for every pattern that references it (unless you want that ofc) Have fun!