Everyone believes in "evolution"!!!

One subtle but important point is that although natural selection occurs through interactions between individual organisms and their environment, individuals do not evolve. Rather, it is the population that evolves over time. (Biology, 8th Edition, Pearson Education, Inc, by Campbell, Reece; Chapter 22: Descent with Modification, a Darwinian view of life; pg 459)

This definition, or description, seems to capture the meaning of one, particular, current definition of evolution; namely, the change in frequency of alleles in a population.

But this definition doesn't come close to convey the idea of common ancestry.

When scientists state evolution is a fact, and has been observed, this is the definition they are using. But no one disagrees with the above.

But everyone knows that "evolution' means so much more. The extrapolation of the above definition to include the meaning of 'common ancestry' is the non-demonstrable part of evolution.

Why can't this science create words to define every aspect of 'evolution' so as not to be so ambiguous?

Am I wrong to think this is done on purpose?