Andy Jassy was the first product manager on AWS, and while there is lore debates whether he "came up" with the idea of AWS (probably not), he's been on it from the beginning and through every single product.

I don't know much about Selipsky or Garman, but Jassy absolutely was/is technical enough to get to AWS to where it was today (or know when not to get in the way of those more technical than him).

Watch any of his interviews from before he was Amazon CEO. The man knew his shit.