Thanks for playing! I definitely get what you are saying when it comes to being more clear on different stats and unlockables. The way it currently works is that characters are unlocked by how close your current stats are to the required "recipe". There's also tooltips for each stat if you hover your mouse over them. It's not explicitly explained but it seems like you eventually figured it out!
I plan on revisiting this game. This was just a game jam entry but I think there's more potential value to be had. I may re-do the whole unlocking algorithm. There would be a character select screen, and the attacks are what are unlocked throughout the game. Each character will start with their unique attacks and maybe a passive trait. A lot of game balancing would need to be done as well. There's a lot to uncover here!