I would like to know if you are required in RDR2 to hunt or otherwise kill animals in order to sustain yourself or to progress through the storyline.

I would love to buy the game to explore its huge open world, which is more of a reason for me to play than to achieve the game's real objective.

But then, while it does not bother me too much having to kill adversaries in a game, I think having to kill an animal would ruin it for me.

All (or at least, much) of the crafting requires skins/pelts from animals (in particular, inventory expansions). Someone who has played more than me could tell you if you can buy these from traders in the game, but my experience so far has been that there's a fair amount of hunting required. You also need to supply the camp with food and the 'normal' way to do that is via hunting though in theory I think you can just give the camp $$ to take care of that.

There are two main story missions that involve hunting that can't be avoided. The first one involves hunting two deer in the first chapter of the game. The second one involves hunting a bear early in the second chapter.

There are also some parts of the story where you have to shoot wild animals like wolves, especially in the first chapter. And you will run across aggressive animals while roaming free as well, and they'll kill you if you don't shoot them first.

The crafting aspects also involve animal products, but you can probably ignore them. The advantages are relatively minor, it's mostly just increased inventory size. You can also buy the improved satchels after the end of the main story without hunting.

You need to eat somewhat regularly in the game, but you can buy food in stores. It's much cheaper to hunt and cook, but it's easily possible to survive without hunting. I don't think anything happens if you don't provide provisions to the camp, but I never tested that fully.

But in general, if you strongly dislike hunting it's the wrong game for you. I would also warn you that many aspects of hunting are very realistic. If you don't hit the deer fatally, they will make heartbreaking sounds until you kill them. If you strongly dislike even virtual animals suffering, don't play the game.

Yes, to a point

I don't believe you need to hunt continuously throughout the game, though I haven't played much so can't say for certain. However, there is at least one story mission where you will hunt deer.

The Aftermath of Genesis

This is a story mission in Chapter 1 where you hunt down 2 deer. The mission objectives are as follows (from the link):

1. Talk to Pearson in the camp


2. Follow Charles to the hunting ground


3. Dismount from your horse and take your bow from its inventory


4. Crouch down and follow the tracks


5. Kill the first deer near the river bank


6. Kill the second deer on the other side of the bank


7. Go to one of the carcasses


8. Pick up the deer then whistle to your horse


9. Stow the deer at the back of your horse


10. Mount your horse then meet up with Charles


11. Ride back to camp

Although you can play, explore and complete the game without hunting (outside of the scripted story missions), you'll have to keep travelling back to town to get more food. However, there are plants/herbs that you can gather and eat.

Having said that, hunting is fairly fundamental to the game in terms of gaining food and crafting supplies, and as a consequence, increasing your stats.

The game rewards you for humanely killing your prey in giving you more meat and better quality pelts. This leads you into finding and selecting those "three-star" animals and ignoring the rest.

It's not been mentioned in the answers/comments so far, but fishing is a part of the game as well, and you're given the opportunity to throw your catch back every time.