Nice to have a Java based game. I used to be a java dev. That's definitely a plus for you. I'm sure your theme could have been "Only One Java Dev" :)
Having said that, there's lots of room for improvement, but you are in the right track. Don't be afraid of testing things out and accumulate experience.
Here's mine if you can spare some time playing it. Many Thanks:
https://itch.io/jam/gmtk-2019/rate/463337