For programming languages supported in Godot, the simplest is probably GDScript. It has syntax similar to Python, there are loads of Godot tutorials written for GDScript, and it is officially supported by the Godot team. GDScript is getting some changes in Godot 4.0, but from my experience, the changes are easy to adapt to, so GDScript skills learned now should be usable with Godot 4.0 with very minor adjustments. I would recommend using GDScript if you are looking for the simplest, easiest to use programming language with Godot.
