Cultivating a sense of belonging can be challenging in online contexts as well as for underrepresented students in engineering education. This study used a mixed methods sequential explanatory design to understand underrepresented students' experiences in a Canadian first-year course. Taking place during remote delivery due to COVID-19, we surveyed students about constructs related to belonging and team experience, finding significant differences between men and women as well as between the majority social group (white and South Asian men) and their peers in terms of whether they valued the diversity of the teaching assistant (TA) team, and whether the course contributed to their sense of belonging in engineering. Follow up interviews shed light on some of the differences in students' perceptions and experiences based on gender and ethnicity, and have implications for inclusive teaching strategies in first-year courses, in particular related to designing team activities and providing supports for peer-TA-instructor interactions.