Most red decks running Koth as their big threat will want to consistently hit their 4th land drop on turn 4, and that means running 24 lands rather than the 20-22 you can sometimes get away with in aggro decks.
Though she has a cost of 7 Ink, Clarabelle is a Floodborn character, which means that she has the Shift keyword, allowing her to be played directly on top of another Clarabelle card, for a reduced cost (in a manner reminiscent of how evolving works in Pokemon)
Whenever you came to the game, whichever variant of a blue 1/1 that cant be blocked you prefer, they serve the same role: cheap bodies to exploit cards like Edric, Spymaster of Trest that reward you for dealing combat damage or a place to slap counters, equipment, auras, and whatever else you want to buff your army with
Just be sure not to use them in any official tournaments or events