We may be people, but somehow we still act as particles when brought together in large numbers. Large as even in several hundreds is good enough to exhibit fluid properties. It would be quite apparent from a bird's eye view of a crowd that under normal motivation, i.e. no extermination threats or rare opportunities that increase directional flow towards maybe a store offering sales of over 50%, that as a crowd moves along its way, it flows.
When moving along corridor where human traffic is largely one way, it's quite noticeable that the faster traffic is in the middle of the corridor than at the sides. Even though there is no direct contact with the walls, I believe there is some sort of psychological contact. This could probably arise because everyone has what socialogists consider a social space, where if someone whom you are not familiar intrudes into it, you feel uncomfortable and there's an instinct to move away. This psychological contact makes humans slightly bigger than what we physically are in terms of particles, and makes our interactions rather elastic. It also explains why there's an apparent "friction" between those at the sides of the corridor which causes them to move slower. What about people in the center who are slow? Well, any person who isn't inconsiderate would automatically drift towards the sides to allow faster people to move in the center simply because of a perceived "social pressure".
There will of course be exceptions to this which brings about the next point — consciousness. Matter and particles, physically, are not supposed to be conscious and not have any higher order purpose (i.e. not like us they only want to be energeticall stable, not rich, not happy, not anything else). As human beings, we flout that property and so are probably limited to acting as fluids. However, I have an argument against that. Recall that a mole of particles isn't particularly large in volume and because of that, all fluid experiments indeed involve a vast number of particles as compared to any crowd at the local mall. If it is possible to gather such large numbers of people for analysis of fluid dynamics, then by the sheer numbers, analogous to CLT, the stray ones who are out there to ruin your day would cease to matter in the study. What is more is as quantum mechanics has it, each particle of matter does behave in an entirely random and unpredictable fashion; at least random in our perception. If there was a bigger being observing our movements, perhaps it would also be perceived that each of our behaviour is likewise unpredictable and random.
So I would hypothesise that there is fairly enough evidence to suggest that we behave as fluids under certain conditions. To add on to that, I will then analyse the behaviours of this fluid.