Right there with you on the Cougar lurve. That is a creation totally wired up for fandom. We also tend to assume a little-guy toughness more typical of characters in martial arts movies, but I'm not sure where that is anchored in canon. It's not just the official military rank, which confers a certain hard-earned respect. Possibly we're reading it into shots of him hauling seriously huge heavy guns bigger than he is?
Along with lots of other folks, I like the mental and physical contrast with Jensen, with the puzzle on how they could click and what makes it work for them. That can be endlessly varied for different writers.
Fandom tends to exaggerate all the differences pretty far, to the point that it startled me to see that iconic shot in the movie where the whole team is walking together. Cougar and Aisha are not tiny people, they're just normal when you look at the others, who probably have to duck through doorways!