For a 2 slice toaster, they could make 60 toast per hour. Primitive human hunters had an endurance advantage over all prey, as sweat is a cooling system. They could run long enough to exhaust the prey. I still imagine horses could produce more electricity. Though apparently a horse can travel just 20-30 miles per day, while an average cyclist could do 60+.
600w electrical output requiring 700w cycling power output is not sustainable human power output. TdF riders will usually output 1kwh over their full (4hr ride) day. Enough for 100 toasts