Hello again, thanks for the advice. I followed this tutorial: 
https://lazyfoo.net/tutorials/SDL/01_hello_SDL/windows/codeblocks/index.php and tried both, the 32 bit version and the 64 bit version, I also tried the compiler flags. Unfortunately, it still doesnt work.
The rebuild log looks better now, but it still shows a sort of error:
-------------- Clean: Debug in SDL2Testproject (compiler: GNU GCC Compiler)---------------
Cleaned "SDL2Testproject - Debug"
-------------- Build: Debug in SDL2Testproject (compiler: GNU GCC Compiler)---------------
Linking stage skipped (build target has no object files to link)
Nothing to be done (all items are up-to-date).
This time I used this code (from 
https://lazyfoo.net/tutorials/SDL/01_hello_SDL/windows/codeblocks/index.php):
/*This source code copyrighted by Lazy Foo' Productions (2004-2020)
and may not be redistributed without written permission.*/
//Using SDL and standard IO
#include <SDL.h>
#include <stdio.h>
//Screen dimension constants
const int SCREEN_WIDTH = 640;
const int SCREEN_HEIGHT = 480;
int main( int argc, char* args[] )
{
	//The window we'll be rendering to
	SDL_Window* window = NULL;
	//The surface contained by the window
	SDL_Surface* screenSurface = NULL;
	//Initialize SDL
	if( SDL_Init( SDL_INIT_VIDEO ) < 0 )
	{
		printf( "SDL could not initialize! SDL_Error: %s\n", SDL_GetError() );
	}
	else
	{
		//Create window
		window = SDL_CreateWindow( "SDL Tutorial", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, SCREEN_WIDTH, SCREEN_HEIGHT, SDL_WINDOW_SHOWN );
		if( window == NULL )
		{
			printf( "Window could not be created! SDL_Error: %s\n", SDL_GetError() );
		}
		else
		{
			//Get window surface
			screenSurface = SDL_GetWindowSurface( window );
			//Fill the surface white
			SDL_FillRect( screenSurface, NULL, SDL_MapRGB( screenSurface->format, 0xFF, 0xFF, 0xFF ) );
			//Update the surface
			SDL_UpdateWindowSurface( window );
			//Wait two seconds
			SDL_Delay( 2000 );
		}
	}
	//Destroy window
	SDL_DestroyWindow( window );
	//Quit SDL subsystems
	SDL_Quit();
	return 0;
}
Could it have something to do with the Path variable? Or with the inclusion of the header file? I've seen people mention that on other posts.