yes, you could do that if you wanted to.

But an 2d lookup array would be better

"ground = groundlookup[p1x][p1y];"

I'm afraid that if you don't know how to do that you should learn some pure programming before attempting to create a game.

1 learn how to program
2 learn how to display
3 try to make a game (finally)

You don't determine your game logic on what is on the screen, you render to the screen what your game logic determines. Keep track in your program where the ground is and where your player is, then just draw it all once you know were everything is. The bitmaps are just the paint on the current conditions.