Vast majority of Poles at the time were peasants and peasants back then had no nationality.
Formally the Statute of Kalisz referred to Jews and Christians and for an obvious reason - anybody living on territories under Polish king's rule was subject to the law, not just those of Polish nationality.
However, I think there is sufficient grounds for questioning the blanket statement that peasants had no nationality at the time. Most those who lived on Polish territories were Poles, whether they were peasants or not, and whether the sense of nationhood was strong or not. Hence, when we discuss Mongol invasion of Poland we talk about Poles being killed by Mongols. When Gallus Anonimus writes about The Defense of Glogow he does not write about "classes" of People. He clearly writes about people's nationalities, and he does at leats 160 years before The Staute of Kalisz was written up:Niemcy nakre;cali kusze re;czne, Polacy zas' machiny z kuszami; Niemcy wypuszczali strza?y, a Polacy strza?y i inne pociski; Niemcy zataczali proce z kamieniami, a Polacy kamienie m?yn'skie i silnie zaostrzone pale.
Just to clarify that among those fighting were Polish peasants, Gall's Chronicle is helpful again:
"do walki z wrogiem stanęło nie tylko rycerstwo, ale cała ludność. Zawzięci chłopi znosili drobniejsze oddziały niemieckie, nękali wroga po lasach i bagnach
You may also look into this fragment in Latin
by the same author, and notice the frequent use of the word "Poloni".
When in the beginning of the 13 century the Teutonic order started the policy of settling the newly arrived peasants in the areas they occupied, the settlers were not just any peasants but peasants of German ethnicity. Had there be no distinction between Polish or German peasants then why would have The Teutonic Order settled the lands with peasants coming from areas much farther from Prussia, rather then with peasants living in the vicinity? Was it the peasant's nationality that was considered.
But I still wonder if these priviliges could cause hatred toward any groups
Any sense of unfairness, real or perceived, will cause some form of hatred, particularly when those not considered native to the land find themselves in a better, and sometimes even equal, position as the natives. Nothing changed since those days. Just look at the the Poles in UK.
By the way you still didnt correct your last question. :(
Correct a question? As opposed to answers, I thought questions can hardly be incorrect.