Decentralised and open source social network.
The Home feed (in comparison to Local or Federated feeds) should only show the accounts you follow, but those posts will be made up of original posts by those you follow and anything they boost (as well as responses to and from mutual people you follow). As someone else has commented, you can hide boosts of those you follow by going into their individual profile page and choosing to hide their boosts.
You shouldn't be getting anything else on your Home feed.
Boosts are marked as such and recognizable, the posts i am seeing are common posts from accounts i don't follow. Here in the middle is an account i don't follow, at the bottom is a boosted post. The feed is my home fed in Elk, it is the same on the website.
The posts i was seeing appeared through the hashtags i am following! Totally forgot about those!
Ah, yes! That’ll explain it.
I use Ivory on iOS and it puts the hashtag above the post so I know it’s a post from a hashtag I follow! Quite a helpful feature.
I don't think so, but you can enable "mute boosts" on accounts that boost a lot to clean up your timeline a bit.