The older stalker games are worth it only if you want the story. If you want to experience the gameplay you can download stalker Anomaly for free. Anomaly is a standalone mod that combines the 3 stalker games into one (minus the story) and adds cut content and has been "modernized" over time. It's a much better experience than the original games and the community considers it THE way to play Stalker, and ontop of being a mod it also has a healthy modding community.

I don't remember how beginner friendly it might be (probably not very because the mod gives you a lot of customization options before you even start the game) but I'm sure there are some beginner guides on YouTube. And for the price of free the only question is how much time you're willing to invest to play Stalker. And if you think the OG games will be much easier, not really. No matter what stalker game you start with you're bound to meet the relatively steep learning curve.