Part of the definition is that you in fact play a role. This means making decisions from their perspective as if you were them and their world was your reality. Any game that doesn’t allow you to make informed, meaningful decisions isn’t actually a role playing game.
Naturally, video games can’t really give you total freedom in that regard, as any option you can pick needs to be anticipated and coded by the developer. But there are candidates that fit the requirement somewhat more and those that definitely don’t.
Cyberpunk, while being a fun experience, doesn’t really give you a lot of meaningful choices, at least not in the bigger quests, especially not the main plot. Most often different dialogue choices only lead to slightly different answers and the same outcome. You can’t decide to rat Panam out to Militech when stealing the tank for example. You’re not really playing the role of V, you’re watching their story play out and maybe deciding what to do first and last.
CDPR have their own inhouse example of a better RPG to compare against.
Or does each game just build on top of working knowledge of previous similar Games?
This. There is a sort of gaming DNA that you just internalize over time. I’ve been gaming for 30 years, I just know how that one breakable wall looks, that you need to come back to once you get bombs or whatever it is. I know the difference between a caster, a fighter and a rogue when I see them without knowing the exact details of their ability mechanics in this particular game. My intuition as to how a given ability is most likely going to work is also usually pretty close. Because they are often very similar across different games.
Also if you don’t know and don’t have to have the absolute optimal combination from square one, just pick what looks cool and try it. If it doesn’t work out, try something else. Most games allow respecs nowadays. We learn through failure and repitition.