hi, just had a look.
thats pretty good for a first animation 
there are a lot of the same problems here that I had when I started animating (I still have a couple of them). Most are pretty basic but they can still be pretty hard to see when starting out so don’t feel dicouraaged or anything. It took me a pretty long time to weed out most of them.
the bow is pretty good, i just think the head should til forward a bit more when he’s all the way down.
first is that the hips are moving along straight line paths, which looks a little strange. when you take a step forward, the hips/body shifts closer to the leg thats on the ground (to maintain balance). This also makes the animation look more fluid.
the step forward and punch looks a little awkward. The step forward should be quicker and more forceful, since most of the force behind a punch comes from the hips. The slow step also makes you quick punch look more like a jab. the hips should rotate a bit both before and just as he punches. Also, it isn’t necessary, but if you stick the guys other arm forward before the punch and pull it back as he is punching, it will make the punch look more forceful. If you do go with a faster hip movement, make sure that there’s a little bit of recovery right after he hits.
the main problem with the turn is that the hips rotate in place while the legs move. It would look more natural if he lifted the front leg and shifted his weight to the back leg (turn the hips during this motion). now he’s standing on one lef facing the new direction. put down the front leg. now lift the back leg a bit while shifting weight to the front (no turn). then put down the back leg facing the new direction. the hips also have to rise a little bit when ever a leg is lifted or wieght is shifted.
the box lifting looks pretty good. nice how you had the box rotate along with his arms. I would suggest that you keep his front leg on the ground for a tad longer as he is lifting the box though.
the guy’s head remains completely vertical for the entire anim, which looks a little strange, have it move a bit. you can also use it to build anticipation to your movements, like turning the head before he turns and looking at the box before he lifts it.
heh, I know that was a mouthful but I ran into all of these problems before and I know it would’ve helped me if someone had pointed them out instead of me spending weeks trying to figure out “why does this look weird?”
keep at it, a few improvements and this could look much better. You’ll only get better with practice. also, something I’ve been told and that i’ve found really useful is to go through some basic motions in front of a mirror. look closely at how parts of your body move relative to each other, how the hip moves, etc.
Good luck and enjoy animating, its one of the greatest feelings to bring a character to life .