There are a few ways to look at it. Some exo-biologists believe that humanoid aliens would not be unusual since upright bipedal beings would be more likely to develop a high tech society. Others think that evolution could be radically different on other planets and that there is no reason to assume aliens would look like us. Still others of course believe that evolution of life itself is a very hit or miss proposition and that it might be very rare out there and we might be the one of the very few or even the only one.
The reported close encounters with these 'humanoid aliens' over the decades has always seemed strange to me especially since many of them are bizarre and the messages given to people by the 'aliens' weird also. Then there is the variety of humanoid aliens also which implies multiple aliens visiting or bad eyewitnesses.
I would think it unusual for one species to find their way to earth let alone multiple ones. So again I think we need to ask what exactly are we dealing with?
btw this was a really good read...he addresses some of these issues as well as other current science questions....and on the ET aspect lists the views, positions, and ideas of many famous scientists and he comes to the conclusion that we may well be alone in our galaxy.
https://www.goodreads.com/book/show/187639.Paradigms_Lost
ps: I don't support the' we are alone' camp...but the reasons for us being alone are as sound in many ways as the opposing one.