This is only sort of true, unfortunately. Polaris is a two-star system: Polaris Aa and Polaris B.

Polaris B is much older than sharks, by several billion years.

Polaris Aa appears to be younger than sharks, at a measley 50 million years old, compared to sharks’ 420 million years

HOWEVER it is unclear whether Polaris Aa is actually that young. Scientists believe that, based on some contradictory findings, that measurement may be inaccurate if Polaris Aa is formed from two different stars that merged. In that scenario, the model we use to calculate star age would no longer work and could give wildly inaccurate estimates of the star’s true age

TMYK

Polaris is 45-67 million years old.

The oldest total-group chondrichthyans, known as acanthodians or “spiny sharks”, appeared during the Early Silurian, around 439 million years ago.

It’s not even close.