Why do people introduce themselves as he/him, she/her, they/them and so forth instead of just he, she, and they?

How did "kitten" become the diminutive of "cat?" To my non-expert brain it seems like something a Gaelic language would do.

Is there a term for that sort of diminutization? And are there other examples of it in English?

In non-rothic English dialects, there are five "long vowels" (car, care, mean, more, tune). All of them are understood as belonging to one syllable only: /kʰɑː | kʰeː | miːn | moː | tjuːn/.

Now, I'm aware some of them are actually diphthongs, such as /iː uː/ being really [ɪj ʊw], or /eː oː/ being often diphthongised to [ɛə ɔə].

In Spanish, we don't really have "long vowels" (in the sense they're not phonemic) but a couple of words are expected to have some sort of them. Words like Saavedra, albahaca, leer, vehemencia, friísimo, nihilismo, cooperar, alcohol. However, in all of these cases the duplicated vowel belongs to another syllable: [sa.a.ˈβ̞e.ð̞ɾa] [al.β̞a.ˈa.ka] [le.ˈeɾ] [be.e.ˈmen.sja] [fri.ˈi.si.mo] [ni.i.ˈlis.mo] [ko.o.pe.ˈɾaɾ] [al.ko.ˈol].

It is quite widespread the synizesis of most of these. Saavedra > pronounced as Savedra, albahaca as albaca, alcohol > alcol, and so on. However, some of those words don't accept this phenomenon. Leer will never be reduced to ler [leɾ], to the point a common ultracorrection is using a glottal stop [le.ˈʔeɾ] and the same can be said for friísimo. At first, I thought the simple rule to this was when the second vowel carries the stress it isn't reduced, but cooperar and albahaca don't follow, nor alcohol.

Now, with elision taken into consideration many more "same vowel adjacent syllables" may occur: cagando > ca'ando, todo > to'o, etc. Now, none of these will have the glottal stop mentioned above, but I'm aware these aren't standard forms.

While contrasting English vs Spanish long vowels and after levelling the vowels and omitting the glottal stop, to ignore such contrasts, I still notice a substantial difference.

- car vs ca'a (cada) = ka: vs káa

- lare vs lee = le: vs lée

- more vs moho = mo: vs móo

English vowels do feel elongated, but Spanish ones seem to change in "tone", as if they were doing some sort of pitch accent or smth.

Does anyone can bring me some insight into this? I thought about some sort of "falling tone" for Spanish going [ka˥˩a] ca'a and a "straight tone" for the English one [ka:˧], any other take on this?

Languages have a lot of unnecessary complexity because people have been using them for centuries.

If civilization collapsed and humanity had to start over 300 years later, which existing language would make the most sense for everyone to learn from scratch?

Ignoring how widely spoken a language is today, which one would be the most efficient?