I agree most of these guys (i don't know Valent) would beat Till under some KB ruleset, but i think you are exaggerating a lot here to make your point, yes Till comes from a striking background, he was a good prospect under KB rules and even fought in a tournament that was some sort of SUPERKOMBAT-qualifying if i recall correctly. He did OK and against some guys that today turned out to be pro kickboxers, sure, only mid-level guys nowadays, but imo that proves he had potential and could be a top guy if he hadn't made the transition to MMA. Also, his 44-0 or whatever his KB/MT record is doesn't have names, but it is a important experience and fits "striking background", that shouldn't be ignored, Till has competed in both KB and MT rulesets in the entire world, and considering how early he went for MMA it's totally understandable that we don't know most of his opponents.
PS: Before UFC, some of Till's fights were at 185, against bigger guys. He clearly is much more talented than the usual MMA fighter, and hasn't won many fights ONLY because of his KO power/size advantage, i watched all his UFC fights and some of his brazilian regional MMA, he was outclassing everyone.
Overeem is done, his chin is gone by now, replace him with Ngannou and i would be all for it haha