Cherry is a classic example of reanalysis, when speakers reshape a word because it seems to follow a familiar pattern.
In Old French, the word was cherise, and it referred to a single fruit. When English borrowed it, many speakers treated the final s sound as if it marked a plural, because English often uses s that way.
Once that happened, people naturally formed a new singular by removing the supposed plural ending. That new form was cherry.
This kind of change is not unique. English has a few similar cases:
- pea came from earlier pease, which had been a mass noun.
- sherry also reflects reshaping in borrowing, though through a different history.
The important point is that speakers do not need to study linguistics to change a language. If a word looks familiar, people often adjust it to fit patterns they already know. Over time, that adjusted form can become the standard one.