the current cover immediately makes it clear what awaits in the game
I disagree. What I see is something that looks like a stock robot head icon and a wrongly spelled mill. A robot saw mill perphaps. There is that thing that looks kinda like a saw blade. (And I read your description and still do not know what a mil is, let alone robot mil. The internet tells me, that a mil is 0.001 inch. Is that the size of your jumpy robot head or what.)
But as I said, I am not a fan of platformer games, so maybe it does make it clear to the target audience.
The biggest issue I see, is this: Platformer games are very popular to make. They really are about the basic thing you will get, wenn using an engine after the tutorials. Move a blob around, dodge environment, get to goal, finish level.
So what you want to convey is, that your game is above that level. And I have no idea how to do that. You can use an animation as a cover. But that will only play when hovered.
You can stuff a few words of text in there. Like the difficulty, or trigger words for the target audience.
Why would people want to play this platformer game, instead of another platformer? I guess, because it is difficult. Because the music is good. Because there is a story. Because the graphics is eye candy. Because there is a highscore. Because people care for the tiny robothead. Because it is fun. Because it has clever puzzles. Because it has a cool mechanic. Because it's a combination between a runner and a platformer game. etc. (Some of those obviously do not apply to your game. Best thing you can do imho, is point out the cool things about the game right in the cover in some way, if at all possible)