I didn’t find any reliable source that could explain me the construction “よう出来ている” but one online translator that translates it as something like “there’s the probability”.
Could you help me please?
Sorry, I’m not at your level, but I do have some books, including A Dictionary of Intermediate Japanese Grammar, from which I scanned the page below (sorry it’s a bit blurry - it’s a fat book and difficult to flatten for scanning) .
One definition of 出来る is “for a person to have a particular nature.”
よう here is basically the same as ように would be, but に is sometimes dropped. It turns what came before it into an adverbial clause that can be connected to 出来る.
The basic structure is 人間は [このように] 出来ている, where [このように] is the part describing their nature.
So this is something along the lines of “humans have a tendency / predisposition to look more at the strengths, rather than the weaknesses, of people they don’t outright hate.”
I chopped off the translation at the part where it talks about how that is something that has been shown through psychological experiments, to focus on what the question was about.