Good first attempt at a game jam 💪! Fun to play and collect all the items and gems and see the character evolve.
Gameplay
Nice that you had different upgrades for your character and could only use one at a time. Also that your character evolves is a fun touch. Seen in devlog that you made everything in terms of gameplay yourself. That's definitely admirable 😀!
Some small tips though: I forgot to right-click every time to rotate the camera. In many games that just happens automatically when you move your mouse. Maybe something to try. And the camera also can end up behind walls and obstacles. That's tricky programming in a first Jam of course, but Unity Cinemachine has some tricks you might want to check out or maybe use in another game.
The bonus in terms of items like the sword and staff I would maybe exaggerate a bit more so that you really go much faster and jump higher.
Oh and I was able to get to the chalice before I even had all the gems because of a glitch through the door...😅
Graphics
Coherent low poly style that looked very cute. That you actually see the items on your back and on the shrine is a neat plus. Some extra particle effects would add some extra polish. A minor tip to make the game more unique on download. A custom .exe icon.
Audio
Catchy old style retro background music. Decent sound effect for jump etc. Some more variations would be bonus next game.
Theme
Upgrading your character with items and also the physical appearance enhancement fit well with the theme.
Devlog
Cool that you did it in a video form! Your explanation of what you like about making games is well expressed in it and also how the week went and what you encountered in terms of problems and solutions. Good devlog.
Overall a very well first Game Jam entry 😁!