Regarding The misguided "Thor" race controversy, both racists and antiracists are starting from a false assumption. We have no evidence that the Norse were racist, and we have strong evidence that they were tribal: their pantheon of gods come from two groups, the Vanir and the Aesir, which probably represent a merging of religious traditions, much as the El and Yahu stories represent a merging of Canaanite tribes from the north and the south who were the beginnings of the Jewish people.
Which means that a thousand years ago, if a black guy spoke Norse and wore Norse clothing and knew Norse customs like a Norseman, he was a Norseman, and anyone who heard him speak would've agreed, though they might've asked him when he or his family came to Norway.
Also, Idris Elba is awesome. If you think he can't play Heimdall as well as anyone else, please stop embarrassing yourself on the internet.