ratiocinator
Lightly seared on the reality grill.
It is neither fitness nor consciousness that keeps an individual alive. It is knowledge derived from experience and his genes.
Nonsense. Fitness is defined as traits that aid survival in the context of the environment of the population. You can call the genome 'knowledge' if you want to stretch the definition almost to breaking point, but it isn't knowledge in any normal sense of the word. The ability to acquire and use knowledge may contribute to fitness, however, whereas a single individual's knowledge may keep it alive in a particular instance, it is irrelevant to evolution and fitness.
One individual may appear less fit to a biologist because the conditions under which that individual will thrive do not obtain.
Fitness isn't absolute - it is relative to the current environment of the population. This is well understood by biologists.
The more diversity in the genes of a species the more likely it will survive a bottleneck and the more likely the survivors will be "unusual" compared to those which perished. These individuals create a set of individuals very different than the individuals which died.
You seem to be struggling to describe a situation in which the environment suddenly changes and there may be individuals with certain traits that then become a good fit to the new situation. Again, this is basic and well understood.