I would recommend just challenging yourself more. Defeat Eikthyr with just a hammer and campfires or something with minimal food. I am enjoying vanilla and I am trying out a challenge I came up with -- no parrying, and only hammer, axe for cutting wood, and a knife for weaponry.

I just defeated Eikthyr by applying a ton of fire damage to him with a lot of campfires. That's all I did. I ran behind large rocks when he was about to do attacks, then surround with campfires and pulled him back and forth until he died, which didn't take long. I saw a professional speedrunner do it, but they didn't die. I died three times...only because I don't have his attacks memorized when I am bare naked and trying to set fires. I was more focused on just my stamina bar and trying to kite him solo. But yeah, just gather rocks and wood on the ground and then craft a hammer, get a knife, hunt some deer, summon Eikthyr and have some fun :)

I also have made an effort to make my base only where a previous structure was and I can only build so far. I'll adjust the rules for myself accordingly with each biome.

But I'm going to try to do kind of a "nomadic / semi-pacifist" playthrough. I plan to sneak most of the way in the plains and such and just try to get different mobs to attack each other. I am not going to build many bases, and I won't really try to upgrade my gear so much.

Basically, just trying to find out the more entertaining plays, not necessarily the more sensible ones.

Then I got a permadeath one I'm going to do

And the wolf army one

Then there's the seeds my buddy and I play on co-op where we have slow played (every biome we got to, we built some big bases), gathered lots of mats (especially wood and stone lol), and just enjoyed the time. 250 in game days so far, and we just started taming wolves to build an army to take on Yalgath(sp?) because his AoE attack is just dumb, so we plan to overwhelm him with the wolves (hopefully 2* when we summon him), and get him down before his spawn animation finishes.

Essentially, a couple of these ideas I got from youtube playthrough videos. It can be fun with or without mods. Essentially you can do anything in the game if you think about situations before taking them on. Like building workbenches everywhere you can and hide them, then you can almost build anything anywhere, trap mobs with wood walls and kill them with the pike spikes. Idk.

you can even do extreme pacifist and have to run and evade mobs to nab surtling cores and such

Valheim is your oyster.