The fact that Bitcoin Cash can smooth sail hoping from one hard fork into another proves that the project is de-facto centralized. If it was not the case, there would be some dissidence and therefore their hardforks would result in a surviving chain as well as the forked chain (just like it happens whenever someone wants to hardfork Bitcoin.. all you get is an altcoin).
The only other possibility is that the project is irrelevantly small enough that consensus can be reached, but that is a short lived period in time. Bitcoin Cash's scaling roadmap will eventually face a problem of big % of people not wanting to increase blocks anymore once they feel the consequences of big blocks (if either actual usage starts filling blocks or someone bothers to spam the network to fill them up making hosting nodes a mess, just like Ethereum)
I think so that mainly due to firs-mover advantage. Bitcoin was the first cryptocurrency to be launched which initiated the crypto market. Therefore it enjoys a huge adoption rate and highest market capitalization. It has been able to survive successfully for 9 long years so investors have trust and faith in it. The forks might offer a better solution to the problems faced by bitcoin but they are just not the original bitcoins. Moreover the core miners too have not supported most of the forks with an unanimous consent which is another reason why is this happening around. I dont think so it would be possible to replace this cryptocurrency.