What is the point of rescuing the siblings in the jungle?

In Spelunky 2, when you encounter the jungle stage (2-1) you seem to be able to start finding one of three siblings (triplets?) in 3 separate caves. After rescuing them, they just thank you and you can walk away.

After saving them, I thought they would be playable characters, so I didn't think much of it, however, after searching around the initial floor/starting area, I noticed that they're nowhere to be found.

My intuition, then, is that if you rescue all three in one run, they give you something, similar to Yang (The turkey NPC who rewards you when you gather all three turkeys)

Can anyone confirm that there is a reward, and if so, what? I can never seem to find all three in the same run, and there is minimal information about them online, so far.

After some intense googling, I found this video with 7 views showing that if you make it to Olmec after saving all three of them, they will give you the reward if you take the ladder in the top right corner.

Notably this means that taking the lava route for 2-1 excludes you from being able to get this reward at Olmec, unless there's some other NPC that offers a reward from that route.

Edit: According to murgatroid99's comment there are rewards for saving fewer numbers of them in the same location, I have now confirmed that this is indeed the case, and I received 3 rope for rescuing only one of them at the same location.