He may be the best distance runner in the world, but he's not just the latest iteration of Haile Gebrselassie.
I wasn't around to watch, but Geb was a phenomenon when he burst on the scene, set practically every record in the book, including remarkable times in the 5k/10k. He obviously wasn't the first 5k/10k superstar, but he redefined the sport. Winsome personality, devastating kick, and 27 world records (which may be itself a record). There would never be another one like him.
Except there was. Bekele had a better kick, better endurance, better championship record (albeit with no 10k heats), and on top of that was more dominant in cross country than he even was in track. In my opinion, Bekele remains the greatest distance runner in history, and his double-double in 2008-9 was the very pinnacle of excellence.
After Bekele's injury troubles started, Farah took over. A slightly different runner (more speed, les endurance), he nevertheless took the archetypal Geb/Bekele approach and distilled it to its logical extreme, turning Bekele's double-double into a quadruple-double. While Geb and Bekele would win with their kicks, they also could and occasionally would win from the front. Farah, meanwhile, would do the same thing over and over again, to a field that was unable (imo) or at least unwilling to stop him. Combine that with a relatively weaker era, and Farah is considered a level below the other two, despite an even better record in the races that matter much.
At this point, I think the Geb archtype was played out in the minds of many fans. But Cheptegei has been a worthy successor. World records and global titles in both the 5k and 10k, and world cross country champ to be. Big speed and big kick. No, he's not quite Bekele, but Cheptegei has been a worthy inheritor of the Gebrselassie legacy.
And Ingebrigtsen...is something different. He's more in the El Guerrouj or Komen mold, a grinder, a middle distance runner who can move up and beat the distance guys at their own game. Vulnerable in a kick, but unbeatable two laps out. He doesn't even run the 10k, although he certainly could, and instead is (arguably) the best in the world at both the 1500 and 5k. It's not better than the 5k/10k type that has been so dominant, but it's a bit different than what we're used to, and that's exciting for its own sake.