Why do most animals never seem to evolve over millenia?
How come most animals never seem to evolve over millennia?


The word "seem" in your question should not be disregarded. You seem to assume that cockroaches (or most animals as you say) did not change much the last tens or hundreds of thousands of years. But what do you know about that (no offence here)? Have you actually reviewed many kinds of research that estimate the rate of evolution of different randomly chosen lineages in the past 500,000 years? I think you assume that other species evolved slower than humans rather than know it. And you will certainly put much more importance to the evolution of the gene FoxP2 (involved in language) than to a gene allowing cockroaches to have a better sense of smell. This is a biased view of what is a rate of evolution. It would be much wiser to consider a rate of evolution as something like the number of newly arising mutations that succeeded to get fixed in the population. See Haldane's rate of evolution and the Darwin unit. Please don't make the mistake to think that being smart (or complex) is some kind of the goal of evolution and those that are not smart (or complex) are "less evolved" or that they evolved more slowly.

You also seem to want to point on the evolution of DNA and evolution of habits. I guess you might be appreciative of the evolution of human knowledge and culture. But this is obviously something that does not have to do with genetic evolution but is rather a matter of cognitive capacity. You cannot compare the change of culture and traditions of insects and humans as insects have mostly no traditions.

Now, this is obviously true that different lineages evolve at different rates. Many things influence this rates such as the population size, the mutation rate, the generation time, the selection pressure (which itself might depend on social structure or the rate of environmental change for example). In these terms, I would rather believe of Homo sapiens as a lineage that should have a rather slow evolutionary rate.

Homo sapiens is quite a recent species. And speciation is often linked with phenotypic divergence, with niche competition and niche complementarity and therefore with a high rate of evolution. In these terms, I would believe that humans are a lineage with high evolutionary rate.