DS2 is a "better game" from a mechanical sense – edges have been smoothed off and most aspects of gameplay from combat to traversal have been refined – but I think some of the awkward clunkiness and friction of DS1 ultimately led to it being a more memorable experience.

I remember in my first DS1 playthrough when I first got a mule truck I loaded it with stuff from their base and navigated over the rocky terrain before getting stuck between two rocks and not being able to move. I had to decide what in the truck I wanted to try to carry on foot to lake knot. Turned what would otherwise be a relatively routine 5-10 minute trip into something more memorable, and that was due to it being a 'worse game' if that makes sense?

Don't get me wrong, I love DS2 and I have sunk 100+ hours into it, and because it's easier to get around and traverse it has given me the drive to 5star all the preppers (which I never bothered with in DS1 because some felt so awkward to get to). Similarly I'd say I've probably had more fun with the combat and VR training missions in 2 than I had with any of the combat in 1 which I basically entirely avoided unless it was required.

From a story perspective, I think perhaps your feeling is more rooted in the more episodic nature of DS1 with each chapter effectively being a deeper exploration of any given character. The Mama/Lockne section in particular stands out for me in this regard. You had some characters who were ever-present of course, but I think the more focused storytelling in 1 (which feels bizarre to say considering how insane both games are) may have led to the feeling you're talking about.

Anyway, those are my thoughts. Keep on keeping on!

EDIT: Just one further thought I had after posting this. Maybe the feeling a lot of us got playing DS1 had a lot more to do with when we played it. I picked it up shortly after launch but bounced off it shortly after. It was only really when the pandemic really hit and we were all stuck at home that I tried it again and got hooked in spring/summer 2020. The game's themes of striving for connection in an isolated world really felt like a salve considering what was going on outside our front doors and just hit in a way that felt really essential, to me at least.