I'm surprised about something that players do in the ending

This is just a random thought 😄

Whenever I watch a playthrough, I'm kinda amazed or surprised that players actually think of jumping into the white ball at the end. Sure, there are some who takes time before trying that or some gets really confused of what to do next but I've seen many that jumping into it is one of their first instincts,

I don't know, it just feels like there's no hint that you have to jump into it or maybe I'm missing something?

UPDATE: After reading many of your answers, I guess there's really no specific thing that makes the player jump into it. It's kind of the culmination of everything we experienced in the game - the curiosity, wonder, interacting with glowy balls, and many more. Most of the time, those contributed to the instinct of jumping into it ::)