I just finished my playthrough—it was fun! Here's my score so far:

I took notes as I was playing and tried to organize them into a list below. Some of my points are similar to the first commenter's thoughts (and you've already addressed those in your reply), but I included them anyway just in case!
Issues or points of confusion
- During the first conversation of the game, I was clicking to speed up the text, and when the choice appeared it automatically chose for me! It felt like that might be a bug (on a related note, I would have liked to see an option to have all the text appear instantly).
- I gather that equipment from the humans (whether it's weapons or armor) is all used the same (eating it to attack)? I was confused because the description of some of the armor seems to imply that you can equip it, but I couldn't figure out how to interact with the equipment slots on the slime character screen! (Unless those are there as a joke? I did notice it had things like "legs" and "feet" hahaha)
- I had some trouble understanding or remembering the relative strength of different items. For example, the potion's description seems to imply that it heals less than the seed ("tiny amount of health" vs. just "heals you"), but it seemed to be the other way around when I used them? Some items also felt like they should be a different level than they are (in particular I was surprised that the Elven dagger was the same level as the basic knives).
- I had some confusion around the eating concept; I think they eat the items during combat, but the text after the first battle (I think that's where it was?) seemed to imply that they ate the loot as they were collecting it? Then there's the "we need to get food for the village" plot, which seems to indicate we should save the items for eating and not use them too much in combat if possible (is that going to be a mechanic later on?)
- I was surprised that the cooldown for special moves doesn't reset between battles! Was that an intentional choice? I don't think it's necessarily a bad one, but it was different from what I'm used to (and it made me wonder if I should try to "stall" battles in order to decrease my cooldowns before the next fight)
- Playing on Chrome with a keyboard and mouse, the drag-and-drop gave me some trouble (especially between belt and bag); the item would very often slip out of my "hand" and jump back to its previous position. But I did appreciate being able to just click on an item and then click in a different spot to move/swap, once I figured out how to make that work (and that mode worked really well for me)!
- I had a bit of trouble understanding affinities. It seems like the word is used both for "strengths" and "weaknesses" (and maybe also "resistances", unless I misunderstood)? I started out mostly ignoring them in the first few battles, then eventually started experimenting and had fun trying to optimize them offensively—at least for matching weapon to slime, since I didn't fully figure out the rest of the system. But I struggled with equipping Tanko and Helen! I loved the existence of the scrolls for healing the whole party, those were nice to have as a backup on Helen (though I couldn't tell if they would be able to revive KO'd slimes or not, and they seemed so rare that I never ended up using them). But Tanko in particular was a bit problematic for me despite being my favourite, because he can't really do much while his ability is on cooldown (no support options other than his special ability) and his weapon strengths are so limited (with lots of overlap with other slimes who are better attackers).
- I would have loved a way to access the settings in the pause menu! (Or else just an easy and clear way to save my game, so that I can quickly visit the menu and then hop back in without losing progress)
- I started out just using the keyboard, and it felt confusing at first! It got much better once I switched to mouse (and I enjoyed playing through the rest of the game using the mouse), but I realized later that the option to have information appear when selecting something with the keyboard was off (which explained why I was so confused at first). I wonder if it could be a good idea to have it on by default?
- Very minor note but it took me a while to notice that the enchanted silver arrow had water damage; it might be nice if it had a slightly more magical or water-y appearance? The other enchanted weapons all looked great to me, it was just the water arrow!
A few small typos
- "it will reduce damage the damage I take" (in the tutorial fight)
- "affective" instead of "effective" (I think in the inventory tutorial?)
- "little more then a stick" (in an item description, I think the small club)
Various things I enjoyed
- It was fun seeing the slime towns (the little baby slimes running around and playing were especially cute!)
- The dev dragon
- The slimes' names (fighter, tank, mage, healer??)
- I like that the healing spell shows you who it's going to be targeting (though it took me a while to notice!)
- I also really like that we can see enemy intents! The battle system felt satisfyingly fun and strategic overall despite my earlier points (I'd love to see it developed even further).
- There seems to be a great variety of settings!
- The bag and belt system was interesting! I'm not 100% sure how I feel about having random items pulled from the pool (and refreshing them taking up a whole action), but once I got the hang of it, it did seem to work fairly well.
- I liked the way the game took me from battle to battle automatically! I would have also enjoyed more freedom to walk around, but with some control setups that can sometimes feel tedious (e.g. if I have to constantly switch my hands around between roaming sections and battle sections), so it was nice to have a more streamlined experience. A good in-between could also be to just give the player a few more options regarding where to go or what to do (even if they don't walk there manually)?
- Despite the slight confusion mentioned earlier, I really like the concept of the slimes eating loot!
- I looked at the list of planned updates and they all look really good to me (being able to sell items will be especially great)!
Final thoughts
I loved the premise and I'm curious to see where the story goes! Will they ever make peace with the humans (at least some of them)? I'll definitely be keeping an eye out for future releases!