Any answers you get to this question will be speculative at best, since the common man (i.e. non-nobles and clergy) didn't gain literacy or a historical voice until the Renaissance, and even then examples of that voice will be few and far between for several hundred years.

So non-nobles and non-clergy in medieval Western Europe that leaves us with the peasants and the merchants.

Its pretty safe to assume that the peasants and serfs did not have much of a sense of self beyond day to day survival and their salvation in the afterlife. Life was hard as a peasant on a medieval manor and the only days of solace were the holidays and feast days of the church where one might have an opportunity to go to bed with an entirely full stomach. Since upward social and economic mobility were not an option, the only thing peasants could strive for was salvation in the afterlife.

The merchants in Western Europe have left behind some records thanks to the nature of their trade which give us some insight into what kind of concept of self a medieval merchant might have, and what it might be that drives one in life. Below is a letter from a 13th century Italian Merchant's mother to her son (Taken from the 2002 AP World History Test):

"You know God has granted you to acquire great riches in this world, may He be praised; and you have borne, and are bearing, great burdens. Pray toil not so hard, only for the good of strangers; let some remembrance of you remain here and someone to pray God on your behalf. Crave not for all, you have already enough to suffice you!"

From this it can be assumed that the merchants of Medieval Europe were driven to an extent by religion like the peasants. Also it can be assumed that some were driven by a sense of economic improvement, and possibly even a sense of some sort of social improvement, which is interesting considering the rigidness of the medieval social hierarchy.

Sorry if the source I used was rather poor. It was easily at hand for me and it is a little difficult to hunt down 1st person sources from the middle ages from a class that was by and large illiterate.

I highly recommend you reading Stephen Greenblatt's Renaissance Self-fashioning http://press.uchicago.edu/ucp/books/book/chicago/R/bo3631967.html as well as The Swerve, indeed.

That is a great question that is answered in an essay by Louis Dupre; "Passage to Modernity".

The European concept of self was synthesized with God, and Cosmos. I agree with your professor that modern thought is radically different from pre-Renaissance thought.

Dupre goes into great depth about the Man-God-Cosmos synthesis, and that Man doesn't exist without the other two. One fundamental idea is that thought, order, and ideas do not exist within the private mind of man, but instead in the Cosmos, and Man participates in the God given Cosmos.

I would also agree that we have few primary sources from common man (i.e. non-nobles and clergy), but given the written and archaeological record we can get an idea about widespread ideas at the time.

Hope this helps.

How did the typical Westerner used to think? How did they view themselves and their place in the world? How might their ambitions have differed from our own?

These are excellent questions, but let me problematize the scope of the questions a little bit by asking what "the typical Westerner" is? Even today, I think equating someone from Finland with someone from Portugal, with someone from Vancouver, with someone from Jamaica is tricky-- the only thing really holding them together as parts of "the West" is this sort of tautological (ie. self-affirming circular logic) belief that "the West" exists. If Western means Caucasian, there are plenty of "white" countries not considered Western (say, Lebanon), or countries like Jamaica that are mostly non-white, but are clearly rooted in "the Western tradition". If it's linguistic, there're countries like Finland that don't speak an Indo-European language, or "non-Western" countries like Iran that do. I hope this goes without saying, but if it means Christian, I would point to Ethiopians who have been Christian longer than Western Europeans, and ask if this means atheists in "the West" are not really Westerners. Finally, if it means capitalist, which it often does in Cold War discourse, then we might follow the center of the capitalist West from London, Paris, and Berlin from Europe to New York and Los Angeles after the war, and from there the center shifts to places like Tokyo and Singapore and Hong Kong. So, basically I would argue that "the West" is not a valid historical category.

Just to add a bit more, a scholar named Carl Schmitt wrote a book about the establishment of international law, which he argues, was rooted in Roman public law and theological considerations of the power balance between kingdoms and the Catholic Church, and sparked by the Spanish and Portuguese invasions and annexations of territories belonging to people in the Americas. Colonization, according to Schmitt, led to the development Eurocentric international law (Jus Publicum Europaeum) as a means of defining states and sovereignty, and as Schmitt (a far-right former Nazi) and more recently a whole slew of leftist post-colonial scholars have argued, colonialism turn helped define Europe and what it means to be European.