I guess people are doing a thing where they explain the origins of their character's name so yeah
Serinal doesn't mean anything. Literally it's a name I made up, and I have never been able to find another character named that. It's often shortened to Ser, which is like an old timey version of "sir" but it's only a nickname. Also it sorta sounds like serenade, but that's coincidence.
His last name has more meaning, but it's still pretty simple and actually has nothing to do with his height or build. That's purely coincidence. Lamppost instead refers to the fact that an ancestor of his invented the lamppost and made a lucrative business out of selling them, forming the foundation of today's (in game) company, Lamplight Inc. which is still run by Serinal's father and is a computers and technology corporation.
And finally his middle name, Cecania, belonged to his grandmother who he never met. He doesn't know much about it, and he doesn't know much about her, so he usually just shortens it to "C." on official documents. If he cared to find out, he'd be surprised to know it meant "free" and, leaning that his mother picked it for him, would probably feel a little bit more of a connection with her.
Also ha ha Ser's middle name is a girl's name get the yucks out now.