So you gain 1-3 points on level up, which means you'd average 2, and now he gets 3, so his cheat is that he's 50% stronger than an average adventurer? I know he has knowledge anyway, but for him to be level 2 or whatever the first time he finds the golem and already busting out mid-level spells seems a bit ridiculous even if he knows they exist. Maybe the elf girl has some bloodline thing that lets her cast god magic or whatever at level 10, but that cheat setup doesn't seem like it does a whole lot for him aside from the fact that he was so unlucky at first.
Also, 5 years to fill a jar of something really isn't that long when a single drop can stop a human from aging. 1 cup is ~4000 drops and 5 years is ~43000 hours, so it takes 10 hours to make a drop that would be effective. Why aren't there a ton of immortal humans running around? Maybe there are, but I doubt it'll be a thing that'll come up.