They're brave, not brawny. Brawny is a physical characteristic. It means muscular. I doubt anyone would get into Gryffindor if they needed to be brawny, since they're all 11 or 12 at the time.

Snape, age 11, on the train: If you'd rather be brawny than brainy...
James, age 11, on the train: Where are you hoping to go, seeing as you're neither?

^That's the occasion I was thinking of.

Some of us are, some of us aren't. Godric didn't select students based on brawn.