A question about Destiny vs Destiny 2, and similar games (Co-op)

Hello,

I purchased a PS4 this week, and something I've wanted to play for a long time is Destiny.

What appeals to me the most is playing with others online, but not so much in the style of Battlefield or Battlefront (though that's interesting too), but going on quests with a group of friends, up against a bunch of enemy AIs. Similar to WoW, I guess (though I never played that, either). But my question is, is Destiny 1 dead yet, with respect to that type of gameplay? Now that Destiny 2 is out, should I just buy that one?

I can get Destiny 1 for about 10-20$CAD, but Destiny 2 is far more expensive, and money is an issue. So I may not be able to afford Destiny 2 yet.

If Destiny 1 is basically dead, and I can't afford Destiny 2 yet, are there games with similar play styles you'd recommend? I think Diablo III has that sort of thing.

Thank you