1} It isn't
an LCD according to the specification sheet you cited.
Also take it that the LCD screen is connected correctly as I don't think it would display anything it it wasn't also I've checked it quite a few times.
2} That probably is
true, but you have not explained, let alone revealed a photograph of how you have actually
connected it in Real Life - we see a lot of problems here from people using faulty "jumper" wires in breadboards, or poking wires through holes in modules without soldering them. I have myself encountered jumper wires with traces of lacquer on the pins.
3} According to the only code you cited, you have the 1 second delay after
first attempting to display something; it was suggested you put a 50 ms delay before