What current gen game would you introduce a first time gamer to?

Portal 1

Quite simple and let's you control a twin stick game at a slower pace

Interesting atmosphere and concept can hook people in too

Alternatively a party game like overcooked/ jackbox etc just to show people how social gaming can be
God help me, Diablo 3. It was utter crap up until the first and only full expansion, and took a while after that even to iron out most of the kinks. But right now it IS the literal incarnation of Arcade Gauntlet: Lewt Edition. So arcadey, so Total Carnage... so good.
Other than Minecraft, probably nothing that uses more than one directional input, which disqualifies most 3D games actually.

Thoughts off the top of my head:

--Mario Maker
--Stardew Valley
--If they're into cars, a driving game with a wheel
--Diablo III
--Zero Escape
--Pillars of Eternity
--Divinity: Original Sin
--Maybe Rime as an introductory dual analog game, it would have to be something that doesn't really have combat.
--Maybe FFX would fit that purpose too since combat in it is turn-based. Other than FFXV I'd actually use X as the introductory FF game because it does a good job of teaching the basic rules of FF games.
Uncharted 4. The majority of people who don't play games are horrendous at using twin sticks. They can't grasp how one is camera one is movement. Uncharted 4 with aim assist all the way up on easy is a great way to start someone off. They get to see hoe good games look, how their stories are pretty good or can be, and that games are just fun.

People saying HZD or things like that don't realize how much knowledge of games we all have. Open world games would be terrible to start someone off at.
I'd pick something that's in line with preferences they have for other media or some hobby they have.

If it's something they are invested in, people tend to pick up controls and such pretty quickly.

Also, don't forget things like strategy games, puzzle games or adventures. These are slower paced but can still have wide appeal.
Echoing others' suggestions of BOTW. My girlfriend is very new to gaming, of the 3D kind anyway, and she has picked up BOTW very easily and actually played it much more than I have since release.

Stardew Valley and not quite current gen but she picked up Portal and Portal 2 quickly too.
Don't give them a open-world game. BotW and Horizon are terrible games for people completely new to a controller and who need some guidance to start playing. Light content, like Life is Strange, Minecraft, some Telltale games are all welcome so the person is not overwhelmed with things to learn. Heck, first time gamers don't even know the controller layout. From this first few games, which either has a clear objective or no objective at all the person playing can get a grasp on the controllers while enjoying the experience, you move to more skill demanding games (not Dark Souls), like some platformers and action-adventure and watch them become the beautiful butterfly you nurtured. Remember to know what the person's taste might be. Some might hate slow games a la Telltale.
Perhaps Life is Strange. It's very narrative-focused so people who're more familiar with films should have an easier time adjusting to it and its mechanics are quite simple and straightforward, as well. Oh and it's not too long, either.
Definitely a game you could play sitting on the couch together. Also preferably something with gameplay that's easy to explain in a couple of sentences. As others have mentioned, Inside or Mario Maker would work well. Also, Rocket League.
I've had family walk by and then start wanting to play Journey.

Race the Sun is also my go to for simple gaming concepts, twin stick shooters tend to confuse non gamers.
Breath of the Wild has a really tough start so it might be alienating but I really think your average person would enjoy it more than most other games, if only because it starts immediately. It's also pretty easy to get the hang of and I feel like most people would quickly realize that the game is difficult but manageable. It doesn't really stop you from going anywhere (unless you continually jump off the Great Plateau, the one area it tells you that you need to glide down from)
Stardew Vally

-There's no losing: even if you lose all you health in the mines, you just get dumped out and lose some money and items
-Everything is optional: if you don't want to do something, don't.
-It's not incredibly skill intensive
-It's not horribly violent
-It's charming
-It's a familiar setting to anyone that has a passing knowledge of farming (i.e. doesn't take a lot of extra work to understand what's going on)
-If they get it on PC, they can run it on damn near whatever they want
Until Dawn worked great with my non-gamer friends. As did Uncharted 4, The Last of Us and Ratchet & Clank. I feel like the cinematic games that Sony tend to release have a great effect on non-gamers as they do with core gamers due to the visual spectacle.

Best wishes.
From the mom beats FF15 thread someone said that 15 was quite the game to start someone on, and that statement was odd to me. Are games more complex now that a new gamer could not adjust to new games as well as old school titles? I don't think so, gamers get their hands held to inifity now and there are plenty of titles that could be used to get someone into gaming without it being too difficult. While a technicality, I would have my mom play Bioshock remastered. My 9 year old cousin made it through that game almost completely melee, so I don't think my mom would have any difficulties.
There's a baseline complexity to the controls involved in playing a traditional modern 3D game. It's entirely reasonable to me that someone who had never played games before could more easily get into a tough game with basic controls than an easier game with complex ones.
My GF started gaming with Horizon ZD, really digging it even though she struggles at aiming. She also LOVED Life is Strange (thx PS plus for this one). She also loved TLoU remastered.
My girlfriend fell in love with DA:Inquisition.

Easy mechanics.
Simple, if not particularly good story.
Decent looking.

It built up her chops with using a controller, and now she can play pretty much anything, she even finished Bayonetta.
Inquisition was your gf's first game?! Congrats dude/girl, she's probably going turn into a real gamer, hell, even I struggled to go through Inquisition(not because it's hard, but because it's rough around the edges and I couldn't get into the story), put a ring on her.

Yeah, this would be my choice too, you literally can only press two buttons (aside from the analog for movement): jump & grab. It starts easy and gets harder through progression, the narrative is excellent and the art-style e very good too.
My girlfriend fell in love with DA:Inquisition.

Easy mechanics.
Simple, if not particularly good story.
Decent looking.

It built up her chops with using a controller, and now she can play pretty much anything, she even finished Bayonetta.
There's no way my fiance would put up with all the inventory management in that game.

This does blow people's minds.


I would bang a hot farmer!
Yesterday I let my 4y/o niece sit in my lap and play Breath of the Wild docked with a pro controller. I showed her the controls and let her run around and shoot arrows at trees then go up and grab them. I told her to let me handle any "bad guys" since it was on my Master Mode file and they'd kill her right away. She loved it.
Black Ops 3 (Online)

I actually know several "New" gamers that were introduced with this.

People rag on COD. But it's very accessible for new players.
I gotta say Until Dawn again. I think because of it's cinematic nature and decision based gameplay, it would be really easy for a first timer to get into.

I would also think Firewatch would be good for someone not used to twin stick controls, nor the first person perspective. Plus, it being a more cinematic and narrative based adventure, it would be easier for someone to get into.

I think throwing all the mechanics of a modern game like HZD or even BoTW at someone who's not used to gaming would be super overwhelming.
Something without twin sticks as a necessity.

I tried to hand Dark Souls to my now-wife who hasn't played a game in a serious fashion since the SNES days, and the twin sticks made it utterly unplayed for her. Not saying that's everyone, but I think it's a pretty big hurdle for someone with zero experience to have to control camera AND a complex game.

I wish it was current-gen so I could say Super Mario World.
On some level, giving a first time gamer a controller like a modern console uses and a game that makes complex use of the whole thing is pretty daunting.

I never really thought about it, since I grew up as controllers did, so I had the simple NES controller as a little kid, the SNES and PSX and such into my teen and adult years, and so on. But when my kids started having an interest in playing games, they were totally confused by things like using two analog sticks to move and look in a 3D space.

I never had to even think about that until I was in my teen years and had been playing for a decade.