The reason the US scores a 0.6 in 1789 comes down to how composite data is aggregated and the global baseline of the 18th century.

Yes, people have put thought into this. This is why I trust institutions and not random posters on the internet.

Is WHO a reputable institution? And was it reputable between 2019-2022?

Yes

The reason that US and its allies/friendlies always score high on these kinds of ratings while their enemies/adversaries always score low is because these institutions and 'experts' are directly funded by and beholden to these countries/interests.

Just look at Russia - it's score is highest in the 90s - the most corrupt and destitute time in its modern history, also happens to be when it was deemed somewhat friendly to US and friends.

If an institution told you to jump off a bridge...