Yes, people, even in the relevant fields, disagree about what fossils, bones and skulls tell us. We have found too few fossils to make a perfect complete uninterrupted record of human evolutionary history from modern humans all the way back. We may never have that kind of record. Not every single kind of hominid left lots of fossils behind for us to find. But that does not matter. We don't even have to look at fossils, skulls and bones anymore, skeptic.
We can prove evolution in lots of ways besides fossils.
For one, we have this thing called DNA nowadays. The DNA record supports what we have figured out from the fossils we have found. The DNA demonstrates, without a doubt, exactly the same things evolutionary theory predicted about, for example, the relationship between humans, chimps and other primates.
First, you can observe for yourself that there are far more similarities between chimps and humans than between, say, cats and humans, or parrots and humans, or lizards and humans, or hyenas and humans. The skeletons are more similar, the behavior, the social organizations, etc. are all more similar. That is Darwin-type 19th century observation--what your alien guy is doing.
But then, if you look at the DNA, you see exactly how much closer humans and chimps are to each other than to any of the other animals I mentioned. You do not have to just go by the length of an arm bone or whatever. You can see it in the DNA. You can actually look and see where the genes are similar and where they became different.
We even have mapped the Neanderthal genome, so we know that they and homo sapiens interbred. DNA research is going to tell us far more about non-human hominid species than was ever possible with the relatively small number of fossils. That is 21st century science. What your alien guy appears to know nothing about.
When a completely new, unrelated field (genetics) supports-- or disproves-- what an earlier field (archeology) found, that is just about the best evidence that you can expect from science.
Despite what some alien conspiracy theory crackpot thinks about other scientists faking data and getting paid big bucks for it. What a joke, someone is paying big bucks for fake fossils? Can I make big bucks finding fake fossils from my own home computer with no experience? Is there a Nigerian prince involved? Please have your alien guy let me know how to get one of those jobs!