Reusing f9, landing F9 on barge, and Stainless steel were his initiatives. The SS one was a particularly hard win for him with a lot of internal push back.

Catching Starship on the chopsticks might have been an idea he heard outside of SpaceX, but that he then championed, again to a lot of internal push back, I'm not 100% about it being an external to spacex idea though.

Edit clarity and below

Those are just examples though. And I'm sure there are times as you suggest that people suggest a difficult idea that he then champions as well.

That he can champion these radical things, his idea or not, is still the key point of his leadership that will be lost.

For example, someone must have suggested they use a full-flow staged combustion fuel cycle for raptor. He had to sign off on that. No one had ever designed and flown a engine like this before. The russians came closest making one, but never flew it. The predecessor to this engine in the 60s or whenever, NASA didn't even think it was physically possible to make until the Russians made it.