I'd like to take the time to disagree with much of the answers here. And it has to do with the "are people too" part.
IMO that implies, above all, similarity between mindsets.
Now if those aliens were more primitive life forms, such as microorganisms, it would be entirely possible. Not just small, but primitive. Because if they are small but intelligent, they will be aware of our intelligence, even despite differences in size, lifespan or whatever.
Our lifespan is much shorter than a tree's, but we still know that it is a life form, not some inanimate object. We are immense compared to microorganisms and cannot even see them with a naked eye, but we still know that they are life forms. We can also determine the intelligence of less intelligent species, for example, we know that a dog is more intelligent than a worm.
Going back to people - if they are people and we are people, I'd say it extremely implausible that they won't be aware of this.
They sure could act as if we are not people, we see that in humanity on a daily basis, as little as color, creed or thickness of wallet could determine whether one gets human or inhuman treatment. But that's discrimination right there.
Just how alien would the aliens need to be?
As long as they are "people too" they couldn't be alien enough to miss that we are people too. Fungus could, bacteria could, plants could, but those aren't people.
I'd say that discrimination is the more plausible way to go, but not discrimination based on their superiority complex, but one based on ours. Or in other words - discrimination that we deserve, which is the "good" version of the regular bad undeserved discrimination.
Let me elaborate a bit further - obivosuly they'd be superior, being capable of reaching and colonizing another planet, and allegedly a star system is, despite all promises and pipe dreaming, an impossible achievement for us. Take the superiority of conquistadors over natives and put it on a cosmic scale.
Aliens could understandably and consciously chose to discriminate us because we deserve it. We discriminate each other over nonsense, we discriminate all other life forms, abusing them for our convenience and entertainment. We destroy our own environment and our own planet against our very interest. We are no better than a parasite, a cancer or a plague. And yet we believe ourselves to be the greatest. I personally very much doubt that any species with such a mindset would last long enough to evolve to the point of being capable of interstellar travel. So any alien colonizers would definitely see us not as primitive but as harmful and dangerous, not to them but to our own planet and by extension to ourselves.
In this context, their "discrimination" of us would be entirely deserved, and it wouldn't be any more discrimination than it is to put criminals in prison or to death. That's the course if plausibility is key.
Furthermore, I don't even think that any species could reach the point of interstellar travel on a "people" scale. That would be a super-organism, still made of people, but not reasoning on people level but on super-organism level, something we yet fail to achieve, at least when it comes to one that would act in our interest as species.
So on "people level" they could see us as people, but if they are part of a super-organism, it won't see us as people comprising one, so in a way, they could act as our own cells do when foreign cells enters our body, they are all cells, but our cells make us - a larger scale life form, so our cells will likely treat the foreign cells as our entire organism would rather than how they would on their own.