Taking the totality of life characteristics into account, it is hard to label either bacteria or human being as evolved. Evolution is simply the generation of diversity and the shaping of the diversity by environmental selection.
Also, it is not as if the newly generated species are in any way better than the older one. It is just that natural selection and genetic drift have together led to the formation of a population that cannot reproduce with the original one.
The only progressive trend in evolution seems to be that more and more complex body designs have emerged over time. However, again, it is not as if the older designs are inefficient. In fact, one of the simplest life forms-bacteria-inhabit the most inhospitable habitats like hot springs, deep-sea thermal vents and the ice in Antarctica. In other words, human beings are not the crest of evolution, but simply yet another species in the abundant spectrum of evolving life.
