Piano writing is great, however your song needs some more dynamics (basically, your song needs to have quieter parts, and not just full blast all the time). Like the intro for example, you don't need to have the piano play on max velocity all the time (or feel like it). A great example for good dynamics is Eetu Suikkanen's entry to this jam.
For mixing, when the woodwind was playing lead, other instruments were louder than it which is not ideal. The lead should be the main instrument playing at the highest volume, just like how you did it right after with the piano lead. Also some bass would be appreciated, especially to those kicks but I'm nitpicking at this point.
But definetly work on the dynamics thing, I used to have that issue for a while (and honestly still do a bit) and fixing it can make a huge difference without putting much extra effort into it.