Poland was liberal for it's time, yes, albeit only for the szlachta, a large part of the population that belonged to the privileged class of nobility. Peasants had not so much to gain access these times, especially in the former parts of Poland that are now Ukraine.
People of Jewish faith had strong privileges in Poland in the middle ages, which lead to the biggest diaspora in the world, a large fragmented community that was integrated into polish society in various degrees - as can be beautifully seen in the Jewish Museum in Warsaw.