Why is Elsa… (spoiler)

My 3 year old is in a frozen obsession right now so I’ve watched the movies about a dozen times now lol. I love the movies but after watching it so many times I realized I had a few questions.

Why is Elsa the 5th spirit? In Ahtohallan, she sees that her mom was the one making the calling voice, wouldn’t that mean her mom is the 5th spirit? How does that make Elsa the 5th spirit? I feel like it would’ve been cool that her mom was the 5th spirit and now her spirit (literally) lives on in nature.

And if she is the 5th spirit, why does she freeze at the bottom of Ahtohallan? How can she freeze at all?

Despite it I still think it’s a great movie, I actually love the sequel more than the original