I will respectfully disagree.
I know that it’s common in the Anglosphere to bestow surnames as first names. IMO, these are very hit-and-miss. Some surnames work much better as first names than others. Some simply sound more like first names than others. This is very much YMMV, but for me, Gordon or Cameron = fine. Murgatroyd, not so much. It’s not a common surname where I come from (Toronto area). Even if it were, it sounds a name that would work better as a surname and not as a first name.
Rudyard Kipling - did he go by that in his childhood/among family? His first name was Joseph. I don’t know if he ever used that name, but it looks like his parents at least wanted to give him some options.
You also mention Grover (OK, though I associate it first and foremost with an annoying monster on Sesame Street, as I do Kermit with his frenemy, a more level headed frog). That name seems to have entered into the public consciousness through the name of Grover Cleveland, a President of the United States. That name is also his middle name. His first name was Stephen, and maybe he dropped the first name in adulthood to sound more posh? That seems to be the case with Woodrow Wilson. His first name was Thomas, and he was called Tommy in his family. In public life, though, he dropped it, and was having none of them.
There was a time when it seemed to be not uncommon for up-and-coming people to initialize their first name and go by their middle which, like you said was often a surname (high-born mom’s name?)
For example, as I mentioned in this thread about going by one’s middle name, Honest John, the sly fox in Disney’s animated feature, Pinocchio, is often called J. Worthington Foulfellow in supplementary materials. So Honest John to those with whom you want to be on personal terms, J. Worthington Foulfellow to your would-be business associates. Similarly, Dagwood Bumstead’s millionaire father in the Blondie comic, was called J. Bolling Bumstead. I strongly suspect his parents, wife, etc. called him John, Jake, Jim, or similar, not Bolling, though I could be wrong.
You’re from the city of York, right? Your username contains the Latin name for that city. “Murgatroyd” orginated in Yorkshire, maybe that’s why it’s on your radar as a common name.
By way of comparison, My favorite girls’ name is Leslie (and it has to be spelled that way). This is a nice, simple name, was not rare when I was growing up, and for whatever reason, fills me with this warm, fuzzy feeling. In the novel that I am now writing, I bestowed that name on a very pretty and bubbly female character. However, “Leslie” used to be common as a boy’s name; as well, my friend C. M. doesn’t like it as a given name. He, however, is of an (allegedly) aristocratic Scottish family and he pereceives it as a surname and not a first name. And indeed, I see where he’s coming from. In Canada, “Leslie” as a surname is mixed in with the rest of the great salad bowl that our society is. Indeed, I think I was surprised in youth to learn that Leslie Street, a major thoroughfare in Toronto, was named after George Leslie, a Scot who immigrated in 1824. Whereas in Scotland, it’s probably a more common one, the name of a Lowland clan.