I play a lot of platformers from itch. Are you saying I'm in a minority, and the silent majority is passing up my game because I don't have unique mechanisms? If so, I definitely don't belong here. I crafted the game to meet my desires.
I don't think the game needs a gif. It's a platformer. I would be stating the obvious with a distracting display that some players might consider a spoiler.
If the game you made makes you happy everything after that is just extra icing on the cake. This is the exact same philosophy I've taken with my own game in the over-saturated shmup genre. I want to make a game that pleases me, and if it pleases others, cool.
Even though the basic idea behind a platformer is well-known, a gif is still useful because it shows how the character is animated and how realistic (or exaggerated) the physics are. I don't play many platformers, but one I downloaded recently from Steam was "Ori and the Will of the Wisps". Besides the cool art style, what sold me on it was seeing how the character moved and interacted with the environment.
Not having a gif for your game is like a musician not releasing samples of their latest song or a blockbuster movie without a movie trailer. Heck, even books sometimes use trailers to attract readers.
The human eye is drawn to movement. Use Gifs.
