Blockchain endpoint working

[Bitcoin]

Blockchain endpoint working

I wanna clear this thing that how blocks are retrieved and created in from the nodes using an end point. The end point is basically centralized and have nothing to do with network if i'm not wrong. Is that end point is also running some kinda setup to keep blocks in sync as well as connected nodes?
In a network we have nodes [B,C,D,E,F,G...] and we have endpoint A. Lets say we have to retrieve a block then on which node the request will be sent?

Take example of STORJ in that request lands on one server(kinda end point) only then it broadcast to all. Isn't the centralized system.

Source: Blockchain endpoint working