there's actually a link to the product page for the MOSFET
Good but you didn't say that you said:-
I'm using an 60V 30A N-channel MOSFET like this one:
The "LIKE this one" to me means "something similar to" not "this identical one". Mind you I have only been speaking this language 60 years so what do I know. Probably more than you anyway.
Anyway yes that FET is suitable for what you are trying to do with it, so that rules out an error in component choice.
Not posting it would've given less information to understand what I am describing
No not posting it would give me no clue as to what you are trying to do, posting what you did gives me only half a clue as to what you are doing. If you are not capable of describing what you are actually doing what makes you think any one can spot what you are doing wrong.
As for my question, I am specifically asking for assistance in writing a script that receives analog input and maps that data to a PWM pin which will drive the aforementioned MOSFET to control the brightness of a series of LED lights.
Unless you get the hardware right then you have no chance in doing anything fancy with it. The first thing you must do is to write something that just writes values to the analogue write and see that the LEDs respond. Without that you are wasting your time trying to do anything else.
With that schematic you posted I know how I would change that to do what you want, but the question is do you know how to change it to do what you want. By asking you what you actually wired up I was trying to assess if you did, so that I could put you right if you didn't.
If you don't want help then why ask in the first place.