How is red skull finna be the main villain when anyone except captain america can take him out in one shot.
The Cosmic Cube aka Tesseract used in the first Cap film was barely tapped into, so they could always bring that back. Even in the Avengers film, it was barely touched. And the Red Skull is a genius (though his power hunger got the best of him in Cap), so there's plenty of ways they can use that. And he has all of Hydra behind him.. You could always read some comics to find out how they did it there.
And I don't think Thanos will be a villain in Thor 2. Maybe a cameo. I don't want to spoil anything if you didn't want to know, but it has to do with the subtitle.