Most appointments in the UN system are done on political considerations.
I have personally seen several women being appointed to high positions and make swift careers in the UN system on the basis of being a citizen of a small under-represented country (Malaysia, Sri Lanka) even though both of them had other passports (US, French). But of course they would not be known as US or French citizen. That Ethiopian DG of the WHO has shown that he is not fit for the job.
When the position of WHO DG opened up some years ago there was an excellent candidate but he was from the UK. They appointed a Chinese Woman at the time. Most of those UN organisations have lost their reputation because of this.
And with Saudi Arabia and Iran in UN Human Rights Council it has become a pure joke.
You know something's not quite right if the WHO appoints Mugabe as a goodwill ambassador, as DG Tedros did in 2017.