The puzzles do have fairly set solutions - basically, the final concoction will fill each of the three slots (head, body, feet) using the aspects from the jar of the smallest size that contains an aspect of that slot type eg. the small jar will overwrite any slots it has in common with the medium and large jar, and the medium will do the same for the large.
If you hover over the final concoction in the bottom left (the sparkly potion bottle), it should bring up the contents of all the occupied jars and show which aspects are being overwritten by greying them out - from there you can shuffle the individual shadows left and right to see how that affects the final shadow!
Regardless, it wasn't our intention for understanding how the puzzle works to be complicated/block people from enjoying the game, and we may try and tweak the tutorial post-jam to better communicate how it works! Thank you for trying it out and letting us know how you found it, feedback is super important to us! Thanks for the kind words 💚