For a "beginner", this is a great start! I like this concept of "The floor is lava" for the jam.
As some others mentioned, the player does not stick to the floor. For the second level (and in general with moving platforms,) you should parent the Transform of the player to the one on whatever platform it is standing on and unparent it when they leave it. For the first level, you kinda need to sprint to make the final jump, but since it is on a downward slope, the moment you start running, you leave the ground. Not touching the ground means no jump, meaning death in the lava. unless you find a way to make the player always touch the floor until a steep enough ledge or until they jump, a rule of thumb is to not do just that. I died quite a lot there and it was getting frustrating.
The UI was also quite low resolution. You should definitely try to use Text Mesh Pro, which is included with Unity and will make the text sharp at any resolution. All you need is select UI elements with the " - TextMeshPro" label at the end and, if it is the first time in the project using them, set up the essential assets in the window that pops up.
Apart from that, this is really a great start! I am sure you will improve greatly over time and make awesome games in the future!