For the dialog box, there were a couple things that made pressing space or enter less intuitive. First, with the arrows, it looked like a tutorial that expected you to do the things it was telling you about to advance. Second, tower defense often relies heavily on mouse, and with most of the UI seeming to be mouse based, being able to advance it with the mouse made sense. I started with trying to follow the instructions in the dialog, then tried clicking on the dialog box, and finally fell back to pressing space, because yes, it is a common way to deal with dialogs, it's just that in this case it was not the first thing I thought likely. A good, intuitive, UI can be tricky. People think differently and trying to predict what will work well for everyone, or at least most, is tough. We've done several game jams now, and UI issues have been one of the things that people have commented on as a reason to stop playing sooner. To start, adding a note on how to advance is a quick and easy fix. Eventually, I would recommend allowing escape to exit back to the menu at any time, including during dialog. Adding mouse support to advance the dialog would also be a nice to have feature.
I understand the challenge of working as a solo dev. I spent years doing it solo as a hobby. Now I work with my wife and kids on our games, and it still requires wearing many hats and picking what piece to focus on getting to the next step.