And I really don't get this contention that being the first is somehow crucial to Holmes' character. I can't recall a single story where "I'm the first consulting detective and forensics specialist" came up; he's simply the best, in any era, and that's why he's important.
A Study in Scarlet:
[Holmes says:] "Well, I have a trade of my own. I suppose I am the only one in the world. I'm a consulting detective, if you can understand what that is. Here in London we have lots of Government detectives and lots of private ones. When these fellows are at fault they come to me, and I manage to put them on the right scent. They lay all the evidence before me, and I am generally able, by the help of my knowledge of the history of crime, to set them straight."
The Sign of the Four:
[Holmes says:] "I crave for mental exaltation. That is why I have chosen my own particular profession,--or rather created it, for I am the only one in the world." "The only unofficial detective?" I said, raising my eyebrows. "The only unofficial consulting detective," he answered. "I am the last and highest court of appeal in detection. When Gregson or Lestrade or Athelney Jones are out of their depths--which, by the way, is their normal state--the matter is laid before me. I examine the data, as an expert, and pronounce a specialist's opinion."
That set Holmes apart as not just a detective, but a detective for other detectives. He had taken forensic study to a higher level than anyone in the country, or the continent, or the world as far as we know, and becomes, as a result, a somewhat well-known public figure. That would be rather harder to establish for a character today with the widespread application of science to criminal investigation.
Is that
the essential thing about the character? No, but it is a defining attribute. Like any enduring literary creation, the time and setting are part of the author's vision and define the character as much as plot does. The further you stray from the author's vision, the more dilute and ordinary the character becomes. It can still be OK, but it's no longer something original and special. If you grew up loving the character as written, as I did with Holmes, a great change in setting or characterization will ring hollow, but for the wide audience the difference will never even be noted.
--Justin