So, this is how it went. Yes, I did lose a lot of ground to Zara.
I delayed my 3rd city to time it with Pottery. By the time I got it, it wasn't an option anymore to settle corn/gems. I believe it would have been possible to rush the site and delay both Pottery and improvements but... the gems being jungled... the city having no access to river tiles... being far away and costing extra maintenance... I still believe my line was fine/good. I also didn't expect Zara to claim the spot that early.
Corn/gems is, imho, the best spot for city 4. Rushing it for city 3 or 2 induces sacrifices ; the earlier, the sharper.
In my mind, I then went : "okay, I'll settle west of the gems, then."
I still did settle Uxmal first and I also stand by that decision. As a matter of fact, Zara had a settler party
en route when I settled.
Then Zara settled the sugar and I went : "okay, he's my war target, then I'll settle north towards Rome."
Then I went : "hum... maybe settling with cows in the first ring is best and start with a Monument."
You both suggest gifting the city. The thought has crossed my mind but I quickly dismissed it.
I think that gifting cities is mostly bad and the move doesn't really have a place in my play patterns.
However, you both rightfully recognize the uselessness of my settler (for which I paid 3pop)
I think you both point out the right play
starting from now. City 5 is a junker, now is not the time to settle a junker city 6.
Now, what I really think is that building this settler was a mistake to start with.
I should have recognized earlier its low-to-negative value and tried to get overflow hammers from another build.
It's conspicuous that Mutal still lacks its Library. I could easily have put 15-20 hammers into that Library and still complete the Pyramids t70 eot.
In the same line of thought, during the last 12 turns, Chichten Itza has contributed a settler and a worker. I do believe the worker was another mistake and the Library should have been 2pop whipped instead.
End result : no awkward settler, 1 less worker (still 7 for 5 cities), 2 extra Libraries.
Thank you both for your input, cheers
ps : sidenote on losing the horses. I think this is a Deity difficulty thing. After losing the corn, that whole area is very awkward to settle (mountain ranges, border pops, low commerce, jungle tile). I was a little disappointed to lose the area but I will mention that up to Immortal, it's probably possible to claim it all with an organic development, i.e. without resorting to far away grab cities.
pps : there's an unclaimed clams 4N of Gondar. I'm not confident it's a reasonable settling spot (500 culture will be coming). Maybe it is. It's a convenient point to start an invasion (yes, Rome is plotting, I know...).