The Audio and the Music Piece
You read the title. Anyways I would love to make the music more authentic and more to Peer Gynt Suite No. 1, Op. 46: I. Morning Mood and somewhat like Also Sprach Zarathustra, Op. 30 - Strauss
*Disclaimer I only the basic understanding of the Cello and understanding a void amount Piano
You cannot “fix” a music piece, there is no right or wrong in music.
And also, you mean you want it to be like In the hall of a mountain king?
It is not major and minor at the same time, it just changes to another key like in many other songs.
I have some ideas for you, try to think of a melody first. From what you made it seems like it is through composed which is like japanese music, it doesn’t follow any forms like ABA. Try to think of a melody first, and then keep on changing the melody later on like variations.
And also for the “changing minor and major” part, you can try to do it by using relative key. For example, the relative minor for c major is a minor, so you can make a melody that is mainly c major, and then change the key to a minor but with the same melody and some embellishments / improvised melody.