Good is really what is approved of and bad is what is disapproved of, and also what acheives the results of a preconceived program. In reality I don’t think there is an objective good or bad implanted in nature, but different natures interpret facts as good or bad depending on their affects and relation to those facts.
In a pragmatic sense you could say there exists “evil”, because we have created the term and have defined it. Oxford defines it : “Profoundly immoral and wicked:” but even that definition doesn’t demand a value judgement. Someone could come along and say immorality and wickedness is good for this and this reason, and potentially their reasoning could be logically sound.
But in the end good and bad are interpretations and as assertions which stand alone they can be denied on the basis of prejudice alone. Nietzsche for example backed up his interpretations with considerations such as, the old morality of good and evil was based a false conception of reality that saw the universe governed by a perfect diety who willed the good, so to interpret the world in the old sense is to interpret it falsely, and so forth.
Creating a new interpretation (or spreading one) requires a series of steps, logical arguments, facts, or even just tempting potentialities, all the while aware of how conflicting interpretations might view these same facts and potentialities.
I think that really morality is an interpretation that supports or is consequential of the structures of life as they progress, and this goes for all interpretation and not just morality, which is not to say it is necessarily the way of truth (which is an important distinction).
Because interpretation is an aid to understanding the world as well as dealing with it psychologically, dominant interpretations are generally attached to the various social strata in different ways and coloured by their current activity and perspectival relationships.
As for philosophical truth, I do think it is beyond good and evil, it simply is, and we attach value to what exists after the fact as ways of dealing with it, and because it is part of human psychology to experience affects.
When Nietzsche attached valuations to different things it was part of a political program and was a result of philosophical inquiry, it was truth in itself reached by philosophical inquiry.
It is true that he may have felt that the new valuation of good and bad was part of a philanthopy, that is, that it would benefit humanity as he saw it, which is another story and another inquiry.