I did not find how to fix the error of not finding the header files, but I since learned that the workflow is really different from my experience with Unity, while Unity compile the solution each time I saved a script, by following a udemy tutoriel with unreal engine 5, it seems each time i am really ready to compile, i must close the Unreal project, and then compile in visual studio,
I have also been recommended to completely disregard Intelisense, So yeah…
still works but seems weird but i got used to it.