Pokemon Gold was my first "technically RPG" RPG. Though some people think that is not a real answer so I will say Final Fantasy(Yes the original) in 2015. Yes I know I was late to that party.
What is funny about Final Fantasy is that it started my RPG crave as I go back and played every famous RPG I can get my hands on. I played so many RPGs in the last 3 years that it practically revived my gaming interest. Just in time for the Switch! Thing is that I am not done! Nowhere near it. I only played up to Final Fantasy 7. I am trying to get through Dragon Quest 2 right now. I played Ultima 1-3. I even got into some modern RPGs like Xenoblade.
Actually some people consider Monster Hunter an RPG. If that is the case then my first Non-Pokemon RPG is Monster Hunter Tri way back in 2010. Some people also considered Zelda an RPG but there are whole sects of the internet preventing to say that. (The first Zelda I completed was Ocarina of Time). So to avoid fights I won't consider is an RPG for now.