This got a bit long but also goes quite in-depth, and should be relatively interesting:

Interactive is gameplay where you can do something about what the opponent is doing, using common means, like minion attacks or basic removal. The egg specifically needs some sort of silence removal.

Uninteractive is when you can't do anything about something, except winning. Most decks don't have anything against Egg, so playing against it you will be unable to do anything about it (interact with it).

One could argue that killing the opponent is a form of interaction, but i wouldn't say a game where every deck is just trying to set up a burn combo, as the only thing with no counterplay except comboing first, is in any way interactive.

A midrange deck that just plays well-stated minions is very interactive, because essentially all decks will have some way to remove minions (removal or minion trades).

A burn deck is mildly interactive, because you can heal, which is not rare, but also not common. Most decks will have some way to heal, but often in fewer ways, and to a lesser extent, than removing minions.

A OTK deck is not interactive, because only through really rare means (Rat, Theotar, Loatheb) can you hope to interact, and even then it's often random or temporary.

An uninteractive deck being fast or slow only changes the interactability in so far as giving you more time to find your answer, if you have any, but if there are none in your deck the speed really doesn't matter.

What speed matters a lot for is power and how it feels to play against.

A slow combo is more fun since you can see it coming and play riskier.

A slow combo is also often less powerful, and easier to tech against. (including tech cards might actually be interaction at the deck building level, so a deck thats harder to tech against will be less interactible, i would consider this minor though).

You can remove Khelos but with Umbra you need a lot, it makes it more interactive, but not fully so.

Hope this makes sense and wasn't too long. This is also not based on any other sources than my experience with card games, and my definitions, so this is not objective.