How can the lightning network can be benefit for transaction between two people if they need to make two transactions on chain for opening and closing the channel. This makes no sense or I don't understand how is it suppose to work.
I can see the benefit for B2C transaction, but not for normal people
It's like an internet connection. You don't sign a contract with a new ISP and run new wires to your home each time you want to access wikipedia - you just have your router connected for any time you need to send or receive data. Same for LN, it stays connected through a handful of channels and you can route through them to any node (practically) on the network.