To serve man it starts out where all promise to the human races dreams and solve all our problem. It has many different elements of science fiction, They had intellectual excitement, high adventure, ambiguous, and suspension of disbelief. It introduces aliens with advance technology which is intellectual excitement and suspension of disbelief. It high adventure was if the aliens were telling the truth or not. It had an ambiguous where at the end you find out that the alien were lying and it everything is not perfect.
The idea of being able to control our evolution and became something be control is a very interesting and cool idea. But it a little scary to think we could possible be ranking and saying these genes are not worthy and should not be used. We would start like a rating system of what genes shouldn't and should be progarm into our D.N.A. and we would stop seeing diversify of our new human race and all become the same humans essentially.
I think usually in science fiction there is this fear that alien would be more advanced them us or equal. But in 'The Invaders" human are the superior and what seems to be the aliens end up actually being humans. This has an ambiguous ending where everything you think you know is flipped right at the end of it. It a very common thing to for science fiction stories to have an ending like that.