Very interesting gameplay concept, I bet programming the expanding lava must've been challenging. Would've been nice to have some sort of indication as to when it would expand so as to be able to know when it's safe to pass by, but it's not a big deal and the game is still fun. The chute showing your ores being collected is a very nice touch too.
A little tip though, you seem to have made your ingame music a positional sound source and it appears to be coming from the top left corner, this causes it to play mostly out of the left speaker/headphone ear. For music and other sounds that are supposed to be "in the player's head", you'll usually want to use an AudioStreamPlayer rather than an AudioStreamPlayer2D. Another tip regarding the music would be, in a game where you can quickly die over and over like this, to make the music a node that can persist between retries so as to not have the music restart every time the player dies. I don't know what your project structure is like, but an easy way to do this could be with an autoload.