That is the March in D major, but it is obviously in C major in your score! Undoubtedly some fool thought it would be more appropriate for beginners transposed into C.
Trouble is, although C major is easy on the eyes, it is very difficult for the hand!
All the white keys are equal length, but all of our digits are not equal length.
At any rate, I heard quite a bit of monkeying around in the 2nd half. I think your left hand got a bit mixed up.
I personally feel that you play many notes too short. As though you are slightly impatient. Hang on to the notes slightly longer. Think of these detached quarter notes as being separate bows on a cello or violin. Right now they sound a bit like pizzicato.