I am aware that the Ancient's are an all elf gang (although I heard that one of their chapters does accept non-elves, maybe Chicago or New York?). The pair who raced Belial did include one elf (the rider) while the other (the rigger) was human. Now the elf in this example would be an obvious in if she wished to join but even the human might be given an invite because of a combination of several factors.
First is impressing Belial himself. Even if the race wasn't at Belial's 'full power' the rigger showed he knew his craft. Second, Belial, although likely to be an Ancient for life, isn't your typical biker badass. If you use his appearance in the 4th edition Book 'Elven Blood' as a baseline he's actually very charismatic and chill. At the very least he didn't appear to have a problem hiring non-elves to represent him in his bid for Sting's position. Third, Tir itself has gone under a lot of shifts by '72 (the placement of game), even allowing non-elves to be included in positions of power.
Now if we were talking Green Lucifer or any of the other Exiles from Tir it would be a none question, they'd only let in an elf. But given Belial's background in Seattle, his willingness to work with non-elves, and the changes in political climate I think, if he was impressed enough, he might consider letting a human in to his chapter.
Now will it be easy for said 'round ear'? He** NO! If he does choose to take up Belial up on the offer I plan on every other Ancient he meets spitting the ground he walks on. I'll probably even have Green Lucifer come up to figure out if his son has gone crazy and deal with the situation himself. That'll make for some great games
As for the possible 'Savage/Bloody' nature of the two tests in question I don't know if the Ancients are really THAT blood thirsty. Yes, they will kill their enemies but they're not psychos like the Halloweeners or a hate group like the Spikes. Using 'Elven Blood' as an example again, not only were the 'runners' in that not allowed to kill the opposite team but if they lost and Belial had to resort to a trial by combat against Sting it was only to first blood.
Are the Ancient's tests bloody? Absolutely! Are they willing to kill enemies of the gang as a part of these tests? Yep! But I don't know if they would expect a prospective member to go after said enemies without the rest of the gang. The Head part might be like tossing a pig or other animal head through a window of a rival's house/bar and then making an escape back to the Ancients but I don't know if it would involve tossing Humanoid Heads. Seems too morbid for the Ancients.