I think the reaction described may also have a lot to do with the local culture (social, ethnic, geographic, family, whatever).
Kids tend to be impatient, so being near the front of the line is almost always desirable How often do you line up to be marched to the ovens? [okay, that one is easy: pretty much “once, tops”] – but I never saw the kind of possessiveness and self-identification with ‘first in line’ that you described when I was growing up. We did recognize that there were certain unfair assymmetries - if your name began with a ‘Z’ , you were more often at the end, even if the criterion wasn’t alphabetical order [e.g. you may be marched out of class by rows, but the original seat assignments may have been by alphabetical order] We simply accepted this, and the more justice minded among us might protest “but Timmy is always last!”
I can’t recall ever seeing “possessiveness” of being first in line unless a teacher or parents failed to exercise their responsibility to assure even distribution of the spoils of chance. Admittedly many really never gave it a second thought. Either they only wanted to herd us from A to B with minimal inconvenience, or they had some unexamined notions of what constituted ‘fair’
The same applied to my kids and their friends. If one tried to cop an attitude, they usually responded fairly readily to a calm “we don’t do it that way here” or "That’s not very fair, is it? There are, of course, exceptions, but let’s just say this usually wasn’t their only ‘issue’.
Of course, we’ve all seen kids where such attitudes seem traceable to the parents (This was especially evident with my patients.), whether it is intentional "go-getter"ism or blithe unawareness of the attitudes they are fostering.
My point is not to slam the adults in these kids lives. It’s simply to note that, in my experience and according to the developmental theories I know, a moderate interest with place and order is normal, but it’s honestly not much more than with adults; it’s just expressed less discreetly. However, any number of adult policies and beliefs can inintentionally create an exaggerated emphasis on “place/rank”
In some families, age order can have the force of law (either oldest or youngest first). Many children become wedded to whatever folk rules get them their way, e.g. some girls assert “Ladies first” to a degree most woman would find embarrassing.