There are various tools you can use to make games such as marmalade or unity3d for android
However, the android UI system is the main barrier preventing you from just porting something across from java or c++ or whatever else. In any case, some stuff is just easier to do using the android framework rather than manually doing yourself in opengl-es or with your own drawing code (such as displaying and updating a text-string score)
Generally, I'd suggest having a play with making some simple apps that explore different UI elements of android, as well as following some of the tutorials on the ANDROID DEVELOPERS WEBSITE. Then look more closely into whether it is easier to port some game over, use one of the above mentioned tools or try and do everything yourself using the android framework and java/c/c++
Also, android 2.2 you can use opengl-es 2.0 if you decide on 3D games. Otherwise higher api level will only impact on the game if you are trying to do something really specialist that only comes with a later api level