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.
Disclaimer: I hold STORJ. (Not that it would have any impact on the answer)

What you're looking at here is an ERC20 token. So your question revolves around the Ethereum blockchain.

When a new block is mined, it is transmitted to the nodes on the network. This is accomplished by the miner transmitting to his node, and his node transmits to other nodes, so forth and so on. 

The idea of "end points" you are asking a node, lets say your node, or a 3rd party providers node for information. In an ideal world all nodes have the same exact information. In the real world they can be different but the node software resolves these differences using "longest chain wins". That's why we wait for confirmations. Ethereum works a bit differently as it uses a "confirmed" flag instead of number of times it's seen since the original block it was first found but this is the Bitcoin forum. 

With Bitcoin you can ask any node for "a block" but i think you mean "a transaction". You simply don't consider a "transaction" or "block" to be valid until there are 6 blocks after it. By then it's statistically impossible for it not to "Exist" on the full chain. 

In your final example: Storj doesn't really "land" (or any token/coin on any chain). A transaction is submitted to mempool which is then broadcast to other nodes. A miner sees the transaction, mines it, and adds it to a block. That block is then rebroadcast. There is no way for you to "spend" anything because someone else has to confirm that the transaction is valid and add it for it to show up on the actual chain.

Note: Apologies for any confusion. The question was a bit awkward but did my best to answer the various points in it. I highly suggest investigating how blockchains work and why they work. Bitcoin is a fantastic place to start since this all started with Bitcoin.