1-You kicked at him on the ground.
Could one use this sentence if he was on the ground and "you" were standing?
2-They shot at him in his room.
Could one use this sentence if he was in his room and they were outside his room?
The first one is not natural at all. In the second we are likely to assume, without further context, that both they and he were in his room.
By the way, if you kick at somebody, your foot probably does not make contact with them. If you shoot at somebody, your bullet probably does not hit them.