When my kids were toddlers, I would tow them in my Burley trailer. It was a bit of a challenge climbing out of the park back to the parking lot. Together with snacks and diapers, it may have been 100+ lbs.
Nowadays, I cycle all over the city alone with water, food, tools, spare tube, u-lock, electronics and spare batteries and power pack. The Arkel bag alone may be already over 5lb of heavy canvas. The total weight may be 15 to 20 lbs.