This is an excellent question! As far as my answer, I'm going to try and stick to your parameters of lower-class, working people and not international travelers, but I'm going to touch on tradesmen and guild members as well if that's all right. As far as concepts disseminating into local culture, you're more likely to pick up something like "Saracens are black" from a guy you know down at the mill who's a tradesman than from the lord who nominally rules your area but only comes through a couple times a year.

People of all classes in medieval Europe would have been aware of other religions, but not necessarily in a way to be proud of -- even in regions where the Jewish population had been formally, violently expelled long before, medieval English Christians retained a keen interest in Jewish people as a stereotype of all things negative. Medieval depictions of Islam in Northern Europe often have a similar polemic flavor to them -- while only those who traveled abroad might have first-hand experience of other religions, even those who stayed in Northern Europe might encounter romances and other fictional works recounting crusades, well into the 14th century. Even in the upper classes -- the English royal family in the late 14th century had textiles (including bed-hangings) depicting crusade narratives and encounters with Saladin. These crusade narratives filtered down and were propagated broadly enough to be recognized across class lines. For a very strange intersection of medieval depictions of Islam and medieval depictions of Judaism, check out depictions of Herod in medieval mystery plays -- Herod the Great in the York cycle is lavishly dressed, exceedingly violent, and swears by his god, the prophet "Mahounde". All this despite the Biblical Herod being... Jewish. (Furthermore, Old Testament figures like Abraham and Isaac also invoke explicitly Christian, Virgin Mary-oriented imagery when they pray in medieval mystery plays. It gets confusing.) These plays were performed locally, and other stories in which Jewish, Muslim, and miscellaneously "non-Christian" parties feature were accessible on a vernacular level also. As you can see, this is a little shaky on what exactly Islam is and what Muslims of the Middle Ages believed -- Dante Alighieri puts the Prophet Mohammed in the place in Hell for schismatics and heretics, and more broadly if a medieval Christian layperson knew anything about Mohammed it was that he was a heretical false prophet (who started off as Christian) or that he was a pagan idol worshiped by Saracens.

Contempt for Jewish people in particular remained even when no or very few Jewish people did. 12th century movements like the cults of William of Norwich and Hugh of Lincoln, Christian children whose murder was blamed on local English Jews and grew in retelling to have elements specifically invoking the crucifixion of Christ. These crimes and their ostensible perpetrators and motivations are a starting-point for later blood libel against all contemporary Jewish people. The Prioress' Tale in the Canterbury Tales is another late 14th century iteration of that same trope -- saintly Christian child murdered by nefarious Jews -- and while the Canterbury Tales were produced for a courtly audience it's at least one snapshot of popularly accepted characterization of Judaism even after the expulsion of the Jews from England in 1290.

Perceptions of race -- in the modern sense of racial distinctions on the body, like skin color and facial features -- are a little fuzzier; they sometimes intersect with popular ideas of religion but sometimes they're distinct. Lower-class people in the late Middle Ages might be aware of darker-skinned groups, even if they might not necessarily be able to conceptualize what that would look like -- the North African figure Saint Maurice was patron saint of dyers in this era and there's a lot of art commissioned by members of related guilds depicting him as a dark-skinned black man both because of his origin and because of his name. (Maurice seemed to relate to "maurus" - both "Moorish" and dark and swarthy.) In many depictions like this 1360s depiction his blackness is seriously blackness -- compare that to Lucas Cranach's more naturalistic 16th century Maurice. It'd be hard to say how broadly these images disseminated even into small villages in Northern Europe, but they would certainly be encountered by people who had never left their own country or met a black person before. The idea that some men might be dark-skinned (even if a popular conception of this in the Middle Ages and Early Modern Era was still that residents of warmer climates were burned by the sun -- not yet so much the idea of black people as being marked with God's curse) was not fundamentally unknown even in towns where black people had yet to visit. "Saracens" might be seen as ethnically distinct -- the Song of Roland among other romances identified Saracens as dark-skinned and would have transmitted that idea even to readers who'd never met one in person. Their understanding of other ethnic groups as we know them today was scantier -- Northern Europeans who didn't travel would have been unlikely to ever encounter a person from Asia, their sense of ethnic groups within the continent of Africa was pretty shaky, and you can more or less forget about contact with any indigenous people of the New World But setting aside regional stereotypes of appearance within European countries, medieval English people would be aware that other people in the world looked different, if not necessarily where those people lived or how many of them there were. (Or which people those were likely to be -- it's commonplace in modern discussions of ethnicity in history to assert that Jesus was a darker-skinned, dark-haired Middle Eastern Jew, or even that Jesus was black, but perceptions and depictions of what Jesus looked like in the Middle Ages were pretty firmly "whatever attractive people who live near me look like".