I am not on mobile gaming. So hard to tell, if your game is fun to play or not.

I read both the descriptions on itch and on play store. And I watched the video. It seems, something is missing. Like, what is it supposed to be. Is action runner some known term, so people know what this is? Is there a story? From the little I could gather, your game might just as well be flappy bird with mana and running. But why the plethora of different classes. Are they even different or is this just a sprite change.

If you look at actual rpg those do not have 14 classes, especially not, if they aim for casual players. More like the basic three, strenght, magic and dextery focused. Like Figher, Mage and Rogue.

It left the impression of a mismatch of complex character planning expected from stuff like old diablo games and baldurs gate, but with aforementioned flappy bird mechanics.

My guess would be, it stands and falls with the user interface and the bells and whistles. Or in other words, is your game fun to actually play and eye candy, or not. Since there is no mention of any story, people looking for the casual action runner thing, might not be intersted in the character leveling and vice versa.

Oh, and your game need not suck to have low downloads. It merely needs to be not extraordinary. There are so many games. If you are not lucky, go viral, or spend a ton of money in marketing, why should people play your game, instead of all the other games.