I believe commerce (aka trade) was important to Egyptians because, through it, they received gold. Farmers also received flax, barley, and three different types of wheat were available for the farmers. Flax was the important source of the textile fibre. (Flax is exported to the neighbouring localities in exchange for gold and other exotic branded products). Some slaves were owned by one person, but some slaves worked for organisations like big temples and big estates.
So in short, commerce, aka trade was important to Egyptians because that is where they received riches, types of crops, and I believe slaves as well.