Why does OnClientEvent work without the use of remote event(s)?

Basically, whenever I put onClientEvent with my remote event it doesn't work. But when I don't use it it works.

Client side:

local ReplicatedStorage = game:GetService("ReplicatedStorage") 
local RemoteEvent = ReplicatedStorage:WaitForChild("RemoteEvent")
RemoteEvent.OnClientEvent:Connect(function()
local player = game.Players.LocalPlayer
    print "It works" 
end)
  RemoteEvent:FireServer()

Server Script:

local ReplicatedStorage = game:GetService("ReplicatedStorage") -- Gets the REP (Replicated Storage)
local RemoteEvent = ReplicatedStorage:WaitForChild("RemoteEvent")
RemoteEvent.OnServerEvent:Connect(function(player)
	if player.Name == "JesseSong" then
		print "idk"
	end
	end)
	RemoteEvent:FireClient(game.Players:WaitForChild "JesseSong")

EDIT: OnClientEvent is used to communicate to the server and client multiplte times vice - versa, if you only wante it to do it from the server to client. Then you don't need an on client event - :FireClient.