I think Apple has been innovating, just not so much with the phone. I think the phone technology has basically matured now, to the point where it's much harder to do something truly revolutionary — much like the iMac and Laptops. No one is decrying Apple for not reinventing the desktop computer on a yearly basis, we're just happy if they bring out a faster processor, sharper screen, better GPU etc (see the similarity to the phones).
When the first iPhone came out it was a game changer and they were able to build on it quite impressively during the first few years. Now that phone tech in general has matured, the big innovations are few and far between.
To my mind, AirPods and the Apple Watch are two typical ‘Apple’ products that have raised the bar for those genres in recent years. We're seeing a similar level of progression with the Apple Watch that we saw with the early iPhones, but no doubt this will slow. Some may even suggest that the jump from the S3 to S4 Watch isn't that impressive, but then it's a much more restrictive form factor than even the iPhone, so the potential for innovation is limited.
Then there are the other areas where Apple have been focusing like the HomePod. While it may be seen as a bit of a flop, it has clearly taken up a lot of R&D, and if they don't decide to phase it out, they will no doubt invest more time and effort into the HP2/3/4 which may 'do an iPod' and change the landscape of smart speakers.
I do get the feeling that Apple has slipped a bit since Jobs died — they've made some questionable decisions both in terms of hardware and software, UI and UX, but who knows whether that's just coincidence or genuinely due to his lack of input.
As someone said before (either earlier in this thread or in one of the X Poll threads) it sort of feels like Apple brought out this year's phone a year early. If they'd iterated the 8 into a 9 last year, and then released the Xs as the X this year, I think people would be more impressed (although they would have no doubt bemoaned the lack of innovation last year with a 'boring' jump from 8 to 9 — so they can't ever really win).
TL;DR — I think you're expectations for innovation in a mature and saturated market are too high.