You've just claimed that mankind can't be proven to exist! Technically human beings are "hominids". A hominid is any advanced primate that is bipedal (walks on two legs). There are several species preceding humans for which we have excellent and effectively conclusive evidence for bipedalism. So, no, even leaving humans themselves aside it is not "assumed" that hominids existed. It is KNOWN that they existed.
Leaving aside the little word games, the fact is that there is no such thing as a transitional species between mankind and animals.
I know that the evolutionists, since they cannot prove their nonsense, have to resort to making up new and clever words to cover their lack of any real science.
Now,if you want to call humans 'hominids' that is fine, but they fall under a distinct class, which is not an animal.
In other words, they are 'hominids' are men.