Beyond not having a valid arduino sketch, keep in mind that details really matter.
Details are particularly important when doing a manual install of fm's new LiquidCrystal library. There are very specific instructions for how to properly install that particular library and if not installed correctly, it can have issues.
Included NewliquidCrystal to sketch
What does that mean?
... when I delete ALL # includes besides #NewliquidCrystal AND # Lcd.h ...
What does that mean? There is no header file named "NewliquidCrystal" or "Lcd.h" in that library.
Once you get the library properly installed, you will need to create a sketch to use it.
Do not use the "include library" option from the GUI it will not work with that library.
In fact, I would recommend against ever using it.
Just include the needed headers for your sketch.
The library includes a few examples that you can look at to see what header files need to be included for the LiquidCrystal_I2C class.
And then, once it all compiles, in order to get the display working, you will need to know the i2c address of the backpack and the pin wiring for that particular backpack (not all backpacks use the same pin wiring).
If you want an easier to install library that comes with examples that will work with that lcd backpack "out of the box", you could try installing my hd44780 library package.
It is available in the IDE library manager so you can quickly and easily install it directly from the GUI.
It will auto detect the i2c address and the pin mappings.
It also comes with a diagnostic sketch to test your i2c signals and the internal RAM of the LCD.
You can read more about it here: https://github.com/duinoWitchery/hd44780
The i/o class for the backpack is hd44780_I2Cexp and the diagnostic sketch is I2CexpDiag
I would recommend running the diagnostic sketch first.
After that you can look at the other hd44780_I2Cexp examples to see what header files need to be included and how to create your lcd object for your own sketches.