Not sure what science class you were attending, but they might have left out a few important details. First, there is actual water on Mars. Yes, there is CO2 “snow” that covers the poles in the Martian winter, but one of our landers confirmed the presence of frozen water in the soil beneath that snow. For that matter, we have also confirmed that water exists on the moon, a discovery that opens many possibilities for a lunar exploration base.
Also, the presence of a magnetic field is literally why life exists on earth. It forms a protective shield that deflects the solar wind and charged solar particles that would otherwise blow our thin atmosphere away. It appears that Mars had a magnetic field at some point in the past, but it faded and the sun stripped most of the atmosphere, and liquid water away. The finding of prehistoric bacteria in dried up rivers and lake beds on Mars would show that life had begun to form there before the environment became too hostile for more complex organisms. It’s all pieces to a puzzle that will help mankind’s understanding of how solar systems like ours formed.