Typically, going back to the earliest naming conventions of Wales/Cymru names had very formal structures but weren’t simply limited to patronyms. Individuals had a given name followed by a byname.
Patronyms (ie: being named for your father) were, of course, the most common with an estimated 50% of ye old Welsh names being “ap/ab” (‘son of’) or “verch” (‘daughter of’) or more rarely “Wreic or Uxor” (‘wife of’). The name Gwendolyn Beynon is a patronym because way back the phrase ab Eynon evolved to simply Beynon. Centuries later I inherited it. Essentially something is a Patronym if your identity is qualified by your father’s (or sometimes your husband).
About half as common (25%) were the people named for some notable descriptive feature—the bright colour of their hair (Gwyn Goch), the length of their legs (Cai Hir), the size of their beard (Cynyr Forkbeard), the prominence of their teeth (Arwyn Fangtooth), their temprement (Ewan the Bull or Ewan the Impetuous).
A few (10%) were named for their occupation. In the middle ages a word for ‘Huntsman’ was Cynydd (Kennith) and a word for a singer or bard was Cantor.
Very few (less than 1%) were named by their place of birth – Ewan ab Einion.