The Bond film continuity:
The first five Bond films, starring Connery, followed on from one another, building to a battle with SPECTRE and Blofeld. But the following On Her Majesty's Secret Service, which in its attempt to be faithful to the novel (which preceeded You Only Live Twice) ignored the previous film by having Bond meet Blofeld for the first time, while still keeping continuity with the first four films (a scene where Lazenby's Bond looks back at props from them).
OHMSS's reception was lukewarm at the time, so EON backpeddled and ignored history with Diamonds Are Forever (in which Connery's Bond acts like Blofeld never did something as atrocious as widowing him). Yet during Moore's period, OHMSS was back in continuity, with For Your Eyes Only (and its two follow-ups) depicting an aging Bond mourning his dead wife and finally getting his revenge on Blofeld.
The casting of Timothy Dalton naturally retcons Moore's aging of the character, but the classic 60s Bond films are still in continuity. This continues to the Brosnan era, where the character's backstory still has him as a "relic of the Cold War".
I've need to mention the aging of other characters too: Bond and Moneypenny were roughly the same age, while Bernard Lee's M dies after Moonraker and is succeeded by two Ms, including Judi Dench. Q either retired or died (depending on your view of Desmond Llewelyn's death being incorporated into canon) and was replaced by John Cleese's "R".
This is all void thanks to Casino Royale, a full reboot with a Bond born in 1968, although the details Fleming set out for his character are still there, just modernised. Bond's M is Dench, and he's yet to meet Q or his most famous villains. He has just become a 007 and is edging closer to Connery's brute gentlemen tactics instead of the older Moore or Brosnan.
Ultimately, the belief Bond is a codename is an insult created by those who do not understand the Bond saga or the depth of Fleming's character.