Didn't give much thought to the matching of the avatars to their role, just wrote tham out as they popped into my head :) I'm the female frontend developer that wrote it so I should know!
I agree, this is the first thing that jumped out at me when I was looking at the landing page. I don't know of quantitative evidence that this sort of thing causes harm, but I don't see any harm in mixing it a bit.
The avatars are quite stereotypical: male developer, female designer, male project manager. Why don't you switch it up? There's female developers too.