I don't believe that that is your first animation. It looks more like a "first animation I'm confident to post after playing with the program a bit" post.
I don't know much about pivot so some of what I'm going to say might not be good cnc.
I think you should work on your poses first. When you kick that high, your torso tends to bend down in the opposite direction. And I think kicking that high is almost always executed when the body is turned sideways. Here's a simple illustration to show what I'm talking about:
I know it's harder to achieve that effect on pivot, but I think it's still possible to do if you work hard enough.
I also think you should move the arms a little bit more. They look like they're prosthetic that just got glued on there when they're not in use.
And maybe you should work on connecting your attacks a bit more. People call it "flow". It's when you connect each attack continuously. What you did was make an attack, end it, then proceed to do another attack. What you should have done was while he was finishing his attack (i.e. after kicking), he should have already been preparing to do the next attack (i.e. preparing his hands for the punch). So when the kicking leg on the first kick has stepped on the floor, he would immediately be going for the punch to make the combo more continuous.
Just animate more until you get the hang of the program and I think you'll be able to make your animations look more natural.
And welcome to StickPage!