It's like asking what makes 5 greater than 5. Humans are all significant simply because they have rational minds and are rational beings. A human being cannot impose on others a value or worthiness, because we are rational beings and have independent minds. As you probably have noticed by now this is not me saying these things, it's from Immanuel Kant. I found these lectures on the topic absolutely amazing to watch: https://www.youtube.com/watch?v=kBdfcR-8hEY
It's worth mentioning that all humans are -humans- just like 5 == 5.
However, the fact humans are humans doesn't make them equal. Unlike a number humans have dimensionality. They can be taller, shorter, stronger, weaker, smarter, dumber, richer, poorer etc. Along with any number of other attributes like job, geographical location, father, mother etc.
Equality is a very precise thing and humans are anything but equal.
You need to read some more philosophy (or, I guess, watch some more.) By asserting unconditional equality, you deny the existence of the will. That position can be defended, but I'm skeptical that you're up to the task at the moment.