So I have a funny story about the age you are at and how all that has to do with this particular factor. I guarantee you I am NOT making this up.
My son is 4, and his first experience of remembering Star Wars well was back over a year ago when we lived in our old house, which was a VERY small place and I did not have any inside influences for him to sway toward (no posters or collectibles displayed), nor did he know how huge of a fan I am.
One day he saw Darth Vader on TV and that was it for him. DARTH VADER. He wanted to watch the movies with him in it and so he saw the old ones and was just so into Vader. Oddly, like me, his favorite has been Return of the Jedi and watches it more times than I can count now. He loves Stormtroopers and the creatures like the Rancor and always Darth Vader. He asks about Darth Maul because he's seen pictures and then Anakin, who he knows his story in a nutshell (his words: He was a good guy, got on fire, became a bad guy and he died and got on fire again) HAHAH! Anyway... I have TRIED to get him to watch the prequels, but he just won't sit down long to watch because he complains Darth Vader isn't there. He just gets lost not seeing the characters he knows and I swear I keep trying to get him to watch just so he can have seen the whole story. He just won't right now.
Here's MY view. I DO love movies Like Captain America and Avengers and these newer films. Star Wars though... It was never the amazing effects. It was those characters. You feel like you're watching these worlds as if they were real. Sure you see some composite work in shots here and there, but my god you see these characters in these environments and you STILL believe they are really there. I know Jabba is a puppet, but I cannot see a puppet when I watch the movie. They look like real things. Nothing is distracting, they just look like they really exist and it's so immersive that way to where I don't have to think about effects and those things. It just all works. And CHARACTERS, CHARACTERS, CHARACTERS. We KNOW these guys and could explain exactly the type of individuals they are. I don't think I could comfortably answer if someone ever asked, "What would Padme do?" "What would Mace do?" I don't feel like I really know anyone enough to tell you I feel like I really know them the way they flesh out the characters of the OT, even small characters like Lando. Cripes he wasn't a major role, yet I felt his development and who he was in his short time from ESB to ROTJ in what he was about. Heck, Mon Mothma... Don't know her, but seemed to conduct herself in such a way that she was extremely well respected and felt like someone I could trust. You can almost look at any scum, middle of the road character, or good guy, and you just knew what they stood for, almost black and white.
I don't know, it's so hard to explain it all in short, but there's just a feeling and a rarity of connecting with characters that is there where the OT just doesn't come close. That's what sells me on these old movies. They're just so great.
On a more current movie series that I love... friggin' Captain America is THE MAN. I grew up not liking the character at all, just out of sheer judgment of the appearance of him in the comics, like why would I like some dude who wears a USA flag-inspired suit and be a superhero that I would think is cool??? Well years later we finally get the movie and I get to see what he is all about. COMPLETELY changed my mind about him. The guy stands for everything right that is wrong with our world today. Uncorrupt, a man of true integrity and doing what is right, unswayed by society or government.... Chris Evans plays him SO well, too. I will be devastated if he gets replaced as THE Captain America. There's such great qualities he gives to the character in his performance where I'm not thinking about Chris Evans. I see Cap and I think of Cap. Great character with 2 VERY solid solo films behind him. Anyway that's another story.....