Hey there!
I think many people already mentioned a lot of points - so I won't go into much detail - if theres on point you want more detail on, feel free to ask.
I like the base design and premise of the game. The art assets were nicely chosen and fitting to the world building.
I think as a new jammer (and maybe even new game dev?) you had lots of good ideas, and were able to get them all in but in return had less time for polishing which was needed.
For example - you have player getting hit feedback with i-frames and animations - yet the visualization of it is missing or you added a healthbar to the hud and werent able to connect it to the actual health.
Another example is flying spikes without underground to hold those spikes - this maybe desired but makes me lose my immersion.
Another thing was the background, it seems you were attempting to get a dynamic background / use parallax movement - which would be great if implemented correctly (btw. we stumpled in our game here aswell) - but instead theres a static background and moments later a different static background. Here I'd probably stick to the static background at all.
Nevertheless - its your first game jam and its definitely a complete game - great job submitting!
Love to see more from you in the future!