If you go for something like good has only meaning because god is almighty you will run into problems.
Aha, I thought your god talk was strange but just an example. The whole talk, I was wondering why you have this fiction as the centre of the argument, but didn't realise you only used this context.
Yes, using a construction like a 'god' as the basis of an argument is a fundamental failure of logic.
Good and evil are man-made constructs; but, they are necessary constructs. Giving objects and ideas meaning gives life meaning. Our experiences, those events that happen to us or that we cause to happen, define who we are as a person. We categorize these experience as a part of understanding. If one interaction feels positive and/or gives pleasure to our selves and others; it is labeled right and good. If another interaction feels negative and/or gives pain to ourselves and others; it is labeled wrong or evil. Very few experiences are entirely one side or the other and very experiences are not linked to other experiences; so, our categorizing of experiences is constantly in flux and continously developing.
Yes, all living things need to interpret stimuli in order to fulfill biological imperative of survival, eating, reproducing. We also have the ability to try to step outside our own experience as an imaginary exercise and see that these things are not universal True, but just our experience filtered through our biology and our socialisation and so not take them too seriously.
One really interesting thing with general AI coming soon™ is that we will be able to view how a non-biological intelligence views existence. They very well may lack our foundations of a bias toward eating, reproducing and not dying. They certainly won't be subject to chemical reactions in biological matter. They (I keep saying they, but it might be a singular mind, too) may be completely alien to us and so fundamentally shift our way of thinking about ourselves. It may be like an alien ship landing in our front yard. Too bad I will only see the beginnings of it given I'm closing in on 50.