We don’t need the same volume of developers to have the same or faster speed of innovation.
And conversely if there is stagnation there is a capital opportunity to out compete it and so there will be a human desire to do the work.
Tl;Dr. People like doing stuff and achieving. They will continue to do stuff.
ps it’s too much to claim other people don’t experience creative ideas using AI. You don’t really know that’s true. It hasn’t been my experience as I have had the capability and capacity to complete ideas on my back burner for decades and move onto the next thing.