Overgeneralized ETs?

It seems to me that whenever people talk about aliens they tend to generalize them .For example some people say they visit us b/c they plan o destroying the world, some people say they are from the another dimension, or they are just grey beings. How do we know that there isnt a variety of aliens. Maybe they have different reces and breeds if you will. Some may be electromagnetic forces others maybe humanoid creatures, etc. And what if they different 'breeds' dont know about eac other or they visit us for diff reasons, (curiosity, recon, even their version of tourism.). I guess in realty we dont know much of anything but i just wanna know your thoughts on the subject