Neither was planned. Oda retcons just as much as other mangaka and authors, but he’s better than most at hiding it. Part of the reason he leaves so many open questions during every arc, even why he silhouettes so many characters, is to leave himself flexibility to fill the gaps however he chooses much later on.
Ie when Doffy said “try higher” than Sengoku back in 2010 (?), it didn’t mean Oda had imu planned. It was a way of him leaving himself room to add characters “higher” than Sengoku. (And at the time it looked like cp0 might have been those characters)
More than a decade later, he fleshed out the concept of imu. It fits, not because it was planned, but because the hole was so big that it could’ve been filled in a multitude of ways and still vaguely make sense.
This is also why he throws in “certain events” so often without giving any information about what they are, same as what’s happening in egghead as of 11/2024. A “certain shocking event” is about to occur. What it is going to be could be literally anything. Oda might know what it is already, or he might have no idea but will give us half a year of flashbacks to give himself time to figure it out.
It’s a brilliant technique honestly, he’s hacked the serialized story format.