These are all great images! I like them a lot. So it looks like we've got 2 potential ideas for the player:
a) A robot that can use battery-powered magnets to attach itself to metallic objects (be them floors, ceilings, rotating objects, etc). The robot can use boxes, conveyor belts, etc and parts of its own body to solve the puzzles.
b) A brother / sister team that gets separated and tries to reunite by solving the puzzles. The big sister and her younger brother will have different abilities; there will be levels where you only play using the sister player and levels where you will only play using the brother. The last few levels (or only the last level) will allow you to play with the reunited brothers, in order to defeat the big, bad, boss monster(s).

I know that the robot idea is mine, but I feel that the sister/brother team idea is more emotional / appealing. What do You think?