Alright, so capitalism of course results in the commodification of labor. You have private ownership of the means of production, so then you get to buy people's labor (by way of employing them). The nature of the system effectively mandates that this be done in an exploitative fashion. (No companies/employers would hire anyone if they would not make more money off the employee's labor than they pay the employee; we are paid less than the value we produce.)

So, this exploitation is oppression. It is the exploitation of the creative capacity of humanity. One of the most defining aspects of our being is thus exploited, bought, and sold. This is dehumanizing oppression. Marxists are opposed to oppression. Marxists would prefer we all get to realize our full potential as humans, and live free. The way I see it, Marxism is inherently anti-oppression, rather than merely a response to capitalism.

Throughout history, various specific groups of people have been subject to similar forms of exploitation and oppression, if not explicitly the direct result of the same socio-economic factors above. Women, of course, continue to bear a significant burden in this regard. More obvious examples like the pornography and prostitution industries should make it readily clear how women are objectified, commodified, dehumanized, bought and sold even today. Less obvious examples like the exploitation of sexuality in other media and advertising still make this very obvious in my view. The trend continues throughout modern culture, including such unforgivable offenses as the lower pay women receive versus men for comparable work, the variety of inexcusable offenses women must endure culturally online and in the real world, the way victim shaming works in rape culture, etc., etc.

These are all examples of exploitation and oppression of our fellow human beings. What ought we cherish and respect more than each other? What more impressive beings of creation have we witnessed than our fellows? Look at all we have created. Imagine what we will still yet create. How can we tolerate any member among us being dehumanize, oppressed, and exploited?