Roast me, but... I got problems with my terrain

Not a problem. Now you can see it working hopefully we can get the terrain working too. I noticed from your first screenshot that the terrain has the terrain collider but I don’t see a rigidbody on the terrain. For the terrain collider to work you will also need a rigidbody component added to the terrain also. This rigidbody unlike the player needs to be set to static as the terrain won’t move unlike the player capsule.