Well the camera zooming in and out... I think you may just leave the zoom level alone as long as actions are clearly visible. A lot of (solo) platforming games don't really do zoom-ins and outs back and forth, and they're great. Like, you know, the NES games: it was all just good-old plain simple scrolling.
Also regarding the sprites' resolutions, well they don't matter much as long as the hitboxes match the sprite. Like, you know? Yie Ar Kung-Fu, Tenkaichi Bushi Keru Naguuru, Urban Champion... They're all on the NES and I'm pretty certain most of the characters' sprites don't exceed 32 pixels in height, and that didn't stop people to make games about exchanging blows. But we still get a good look at what's happening no problem. If it's the size of the game screen that's too big, just apply a simple zoom-in on the action. (or whatever game makers do to have the resolution zoomed, idk how it's called)