The kid with super power!

Nah, RDJ is standing in this. He just isn't wearing the heels he has for filming.

No no, lighting is a firebending ability.

I think they are referring to lifting the hammer.

I thought they were implying the kid was Thor, and that the kid also looks like Aang from AtLA. And from there they had extrapolated that Thor was an Airbender.

But really. Thor would be a firebender, because Lightning is a firebending ability.

Well, Aang was the Avatar, so he actually could do both.
But yeah, if Thor were in that world he would be considered a firebender