I'm sorry, but I don't think LeBron is the first of his kind. I see him more in the mix of a Julius Erving or an Elgin Baylor or a Connie Hawkins - a big, athletic, mobile guy in a forward's body.
I think Kevin Garnett is more unique than LeBron.
Ok on that same line of thought, What about Dirk? There has never been a 7 foot player with the speed, range, and jumper quite as sweet as his.
I can go with Dirk on that same train of thought, given that we never saw the younger, mobile Sabonis in the states. And the young Sabonis was more athletic, and MUCH stronger, but not quite as pretty with the outside jumper as Dirk.
The closest I could come to Garnett was David Robinson, and I didn't think that was a good fit.
I'd argue even if we had seen a younger Sabonis that Dirk still is very much in the running due to the talent level in the NBA compared to the 90s as far as big, athletic forwards/centers go. Sabonis would have been one of a kind then. Off the top I can name KG, Amare Stoudamire, and Dwight Howard as very mobile, strong, quick big men now. I guess that is also part of the reason Dirk doesn't get his fair share of love from the basketball community.
As far as physical abilities or style of play goes I don't think there has been a unique player in really long time. There was Dr J in Jordan. Even prior to KG going to Boston there was a bit of Bill Russell in him. No player right no is a 'perfect fit' of another player from a past era. Kobe and Lebron both are modeled after Michael Jordan and Magic Johnson.