Thanks for playing and the feedback. We have added filtering to limit what items are shown in the inventory, and plan to add sorting as well. We need to add a tutorial for the inventory, and I should probably move that up in the list of things to work on. The way inventory is intended to work is that you use the filter to select the items you want for the current Slime, and then use the bulk transfer buttons to move items from the shared bag to the Slime's bag. You can adjust the bulk transfer amount from a list of options at the bottom. This is useful if you want to divide up a certain type of item, such as each Slime gets 5 healing potions in their own bags. We are trying to make the inventory flow quickly and smoothly to keep the game moving along. Only customizing the Slime's belts requires updating each slot individually.
We plan to work on adding more story later this month. At that point you will start with no loot for the first battle and only use abilities. You will get your first loot from that fight. We had been planning to go with the current amounts, but perhaps we will reduce the amount of loot for the first level and let it ramp up over time.