You may say that consensus doesn't guarantee accuracy, but you have to temper this. Scientific consensus is typically correct according to information available at the time, and radical changes in information shift the paradigm to a new consensus which is correct in the same way. To say that 'scientific consensus is historically wrong' is to miss the point entirely; in a field whose raison d'etre is to attain and evaluate new information, all consensuses will be wrong to some extent at some point in the future.
As to the appeal to consensus, what we have to understand is that science generally is populated by many people with many specialised areas of study. No one person can claim to have excellent knowledge in enough areas to establish originally - i.e. doing the work herself - whether any given claim is accurate. So when somebody says, "There is a scientific consensus on evolution through natural selection, mutation, and other means," what she's really saying is that the scientific method is good enough to ensure with a good level of confidence that many disparate areas of study may reach a similar conclusion and will agree on a given conclusion. So we trust that the output of palaeontologists and geneticists has gone through a robust process and that their findings are accurate.
Ergo, on the balance of probability, the theory of evolution almost certainly accounts for the diversity of life.