This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development is uncertain. The character combines 亻 (person) with 榮, but the original meaning and component relationship are unclear.
A person 亻 beside the complex 榮 shape. Without a clear meaning, picture a person standing next to an ornate, flourishing tree (榮 suggests glory or flourishing), but the overall idea remains obscure.
For ケイ, imagine a person named Kay standing beside the flourishing 榮 tree: Kay -> ケイ.