The problem is that what you said has NOT been done.
That you may be unaware of the many ways the ToE has been tested and confirmed doesn't mean it hasn't happened.
Where is the repeated test and confirmation on the skin color variation among races?
In what respect? We know that particular skin colours are specific to particular populations and the degree of pigmentation correlates with their exposure to UV radiation according to their geographic locations, and we also see that the associated genetic variations are consistent with these features evolving in relatively reproductively isolated populations, and that the timescales suggested by the genetic differences between populations are consistent with the estimates for their geographical separation.
This is all fits the expectations of evolution. What other possible tests would you like to see?
What is the conclusion beyond "we are not sure"?
The conclusion regarding skin colour differences between populations is that we are sure beyond reasonable doubt that it is due to the evolution of relatively isolated populations in geographic areas with correspondingly different UV exposure levels.
if we can not be sure on this "modern" issue of evolution, how confident could we be when we study ancient lives that are no longer available? Any simple fact explained by evolution theory would hit the wall of unknown after a few levels of questions.
We can use the scientific method to infer the correctness of the model. We observe the mechanisms and processes of contemporary evolution in the lab and in the wild, and predict what we would expect to see if these processes and mechanisms were similar in the past. Then we observe the available evidence to see whether the real world corresponds to what we would expect if the theory was correct - and we find that it does, and not just in a generic sense; it has been used to make specific predictions which have been borne out by exploration and experiment.
There are multiple independent lines of evidence that are all unequivocally consistent with ToE predictions and expectations, e.g. fossils & their stratigraphy, genetic markers, anatomical & biochemical similarities, geographic distribution, etc., etc.
Clearly, the further back in time we try to look, the sparser the available evidence, but what we've found remains consistent with the ToE as far back as we have fossils. It is also consistent with the evidence of geological and climatic changes over time (plate tectonics, volcanism, atmospheric composition, climate, etc.)
If a model explains our observations, makes novel predictions that are found to be correct, is testable and falsifiable in many ways, but has passed all tests and not been falsified in over 150 years of exploration and experiment, has multiple independent lines of supporting evidence, explains a wide range of diverse phenomena, is parsimonious in conception, and coheres strongly with existing scientific knowledge, and there are no competing scientific hypotheses, it's called a 'correct model' - with the implicit qualifier that all scientific models are provisional, open to revision or falsification. In practice, models or theories that have been as successful as the ToE, are generally accepted as factually correct beyond reasonable doubt.