You're welcome, and if you continue I'd love to play more! I did slopes for the first time myself. At first I had an over-complicated separate stair node that I placed over stair shaped tiles. But what I found out is that when you are adding collision shapes to your tile sets in godot you can click to add a polygon collision.
All you need to do is click the top corner of your slope, the bottom from there, and across from that point, and it will automatically make a 45 degree angle slope collision in a triangle shape, and as long as your player movement code allows for sticking to slopes equal to or lower than 45 degrees, it will work. I suppose this would all be very dependent on what your base movement code is like, but the tileset builder allows for slope collision.
I also removed gravity application to the player while on the ground to allow for smooth movement, since I didn't want the player to go slower up slopes and faster down them.
Also very hype to make some genesis jams now. Thunderforce is not a name I have heard in a while but it was one of my faves on the console.