I have noticed similar things, just like you. Here are mine:

1. More respectful, thought-provoking commenters
2. Being early on a fundamentally different site is cool (federated vs centralized)
3. In really small sublemmies (Less than 10 posters I guess) I kinda get the small village feeling, where eventually everyone will know eachother, which is kinda wholesome.

Because it is?

Because the people are all lovely

I'm a recent reddit semi-convert (haven't left Reddit entirely just yet) and I'm loving it so far

This is absolutely true, and this is how the internet was back in the old days before Big tech and megaplatforms. People would set up little servers on their cable modems using spare laptops. It was experimental, it was imperfect, but it was ours. One side effect of this, was that you had to be at least a little bit smart to get yourself connected to it. Even if that just meant knowing that connecting to it was something that you wanted to do. That weeded out a lot of idiots who contribute low quality discussion. Also, because there is no giant company with a financial incentive to get everybody to use it as much as possible, things were built for raw functionality rather than trying to make them easy for people to get addicted to in 30 seconds. That naturally makes them more usable for anybody with an IQ over 90.

Also, no advertisements. No sponsored posts.

The negativity is definitely less. Sure, out of say fifty comments to a post there's maybe two disgruntled souls. Overall it's conducive to discussion.

Over on reddit I kept to just hobby subreddits for the most part to make comments. Only way to not come across the trolls.

Yes, the clean UI is wonderful. It's good to have something simple. It's also fun to watch something grow.

Of course it feels new, because it is new to many people. :-)

I felt like people were seeing my Reddit posts and comments, and I feel like people are here, as well. As with any commenting website or service, as the numbers of commenters grow large you need to be relatively quick to reply if you want many people to see what you write. On Reddit, obviously that means it depended what subreddit you were commenting on. And surely it will be the same or already is the same here.

The UI all depends on what client you're using. In my mind it doesn't feel like the early Internet, but that probably depends on our relative ages.

Because

Less repost bots. Seriously, I'm pretty sure 1/3 of posts I would see on Reddit were repost bots.

Because everything is small and manageable for mods right now, and everyone is talking to everyone else.

Lemmy also has the advantage that the default "hot" sort favors recency instead of upvotes so that you can get into a thread pretty late and still have your comments be seen.