Decentralisation goes beyond ownership structure. I agree with the fact that a huge percentage of most decentralized projects are owned by a seasoned few, but that does not change the fact that they are decentralized. Decentralisation is could be depicted in the public ledger and transparency of transaction. I recall that one of the characteristics of cryptocurrency is decentralization.
You are not getting it correctly, there can be developers but they may not claim ownership but the top members of the developers can claim the co-founders. Bit that is not what we are talking about, they are centralized in the sense that the top members which are just very few have the majority voting power, what is decentralized about that? DAOs are even most centralized.