It's not possible to increase the entropy of the whole system(universe). The problem with your eating example is that you add things to the system, this IS increasing the total energy of the system as you describe it, and increasing average entropy once you start removing low entropy waste. It makes sense when you already understand the system is open and entropy everywhere is decreasing, but looking at systems in such an isolated way is likely why your teacher developed his flawed views. Outside of theory there is no perfect system (except for maybe the universe), even a double walled vacuum can't keep all the energy in a system isolated; living things don't even try to function as an isolated system, so you shouldn't look at them like they are. Evolution, or life as a part of a larger ecosystem, needs to be considered in respects to all of the other factors interacting with it. This could practically be limited to the Earth, Sun, and Moon in our case. atm

Complexity is also not inherently good or necessary for evolutionary success, that's simply a philosophy we have because of our biased views of life. Bacteria are the major life-forms on our planet, even if they're not doing much living. To compare complexity to height, and from there take the entirely metaphorical height and potential energy and use that as an argument against literal entropy is asinine.