Godot is statically linked to over 10 libraries, and has over 1 million lines of code. That's why the executables are relatively large compared to much simpler C/SDL applications.
Moreover, you should distribute your game in a compressed format (compressed installer, .zip archive, Steam, …), which will help reduce the file size by 30 to 50%. When you do this, I suggest you don't pack the resources inside the executable, but rather besides it (in a .pck file), which is the default in Godot.