spoilers !!!!
the white hair guy, lee jaehon, (who i will call ljh) is part of an alien hive mind (referred to as "Us" by ljh) where they all share the same thoughts (though there is more than one body of "Us," not just ljh). a reason why ljh looks like a lizard is because of "Us" and that is their true form. the human face (where most people see the white hair guy) is a front that shields others from finding out ljh's/us' true form. the reason why kse can see ljh as a lizard is more theoretical as you read more into the story, so the most semi-spoiler-friendly version is because kse is not originally from the DER.
the closest the reader will get to seeing see lee jaehon's real face in other people's point of views because all Kim soleum can see is.. well.. lizard !
stuff gets INSANELY real after part 2 (and even then, there's a ton that happens in part 1) so if you want more information, feel free to ask! i put a semi-spoiler-friendly because there's a lot more to explain if i don't keep it that simple lol

Can someone spoil me why Kim soleum see the white hair guy as a lizard instead of a normal face? Also when do we actually see his real face?