Who were the first people to migrate to America and find the Indians?
I assume that you are asking who the first people to "discover" North America were after the Native Americans peopled the continent. If so, the answer simply cannot be known for sure. There is evidence that Norse explorers had reached North America in the years around 1000 AD. There is an archaeological site in Newfoundland, Canada that proves this.
However, there is simply no way to know if these Norse were the first outsiders to reach North America. They are the first for whom we have good evidence, but that does not mean that we can know for sure that no one reached North America before that.