OK, so you want presentation feedback, and it looks fantastic. Beautiful characters, monsters, UI, everything. If I want to get real nitpicky, maybe I don't like the way the font looks on the tutorial screen, but I have to stretch to criticize that. I think also maybe some double digits numbers have some overflow too -- my screen is 1920x1080 fyi.
As for understanding the game...well...so for most of it, my brain just says, put the big numbers in the squares. I was confused on what my health even was though until the fourth fight, when I realized it was the dice. Before that, couldn't find it and wasn't sure if it was part of the enemy's status box because all the numbers at the bottom were 0. I think also the bleed stat isn't really necessary -- it'd be more clear to just have a number pop up on top of the boss with a -5 in red or whatever, like in your standard JRPG. Your eyes aren't really looking at the UI, so it's hard to really glean information off of it, especially the bleed info.
Now, strategy does come into play at least on the 3rd and 5th fights with slime and diceholder (diceholder I gave up on after like 10 attempts). It takes a while to really understand what's actually happening -- that the enemy is not just nullifying one of your die's attacks/defenses, but actually stealing it and taking it for its own. Since it almost always seems to go after the largest die, it means you want to sacrifice your largest die on defense, then hope the other dice make up for it. On diceholder then, if you get less than 2 defenses, you're basically done, unless you get lucky next turn and get a heal. I think gameplay wise, having different jobs or different effectiveness (or different values of rolls meaning different things) for the different characters would have been better, because unless I'm mistaken, only the healer seemed to have a unique role. But maybe that's why I was having a tough time with the boss -- maybe one of the dice was resistant to getting their attack absorbed or something.