As a technical demo, major issues to look for is the slow pace of combat. It's paced to feel cinematic but this will get old in the first few battles if this is used for a game built around random encounters and grinding.
You can clearly tell that the battle system is built with events as some sort of sprite seem to flash on the top-left corner before fading into the battle. I peeked into the game files and found that's exactly how this game was built. However, this is a system which every unique battle has to be built manually and will cause problems for any project with a scope larger than a jam.
If this jam were to have a technical category, this is realistically a 1 star. This may be a wakeup call to get much deeper into object-oriented programming, this battle system is probably best built as a plugin.
Overall, a 2 star. For every other category, my opinion is pretty similar to what everyone has shared