Humans have always been highly intelligent, they were just limited by the tools of their times. And yes much of their knowledge and innovation wasn’t preserved to be built off of.
Another piece to this is that smartphone innovations have slowed down significantly. I used my Samsung S8+ from launch 2017 until 2022 and couple kept it going longer but it wasn’t getting security updates anymore and it’s performance for Android Auto had intermittent issues, so I sold it to my friend (who’s still using it) and upgraded. But as far as new features on new phones, by upgrading I got a faster display, faster SoC, and more RAM, which are nice to have but not game changers imo, and I lost a headphone jack, micro SD card expansion, and downgraded the resolution of my display (S21). I’m planning on holding onto this phone as long as possible and maybe I’ll upgrade to a foldable if they iron out the kinks and come down in price.